Introduction To ICTs

rmmakaha@gmail.com
INTRODUCTION TO
COMPUTERS
rmmakaha@gmail.com

INTRODUCTION TO COMPUTERS
1rmmakaha@gmail.com
CONTENTS PAGE
HARDWARE...............................................................................................2
SOFTWARE............................................................................................. 84
DATA SECURITY, COPYRIGHT AND LEGAL ISSUES.... 140
FILE MANAGEMENT & FILE CONCEPTS............................. 159
DATA COMMUNICATIONS AND NETWORK BASICS..... 232
INTERNET SERVICES.................................................................... 257
COMPUTER ERGONOMICS HEALTH AND SAFETY ....... 274
ABBREVIATIONS ............................................................................. 286
WORD PROCESSING ...................................................................... 291
SPREADSHEET PACKAGE .......................................................... 291
DATABASE .......................................................................................... 291
PRESENTATION ............................................................................... 291

2rmmakaha@gmail.com
HARDWARE
COMPUTER
 An electronic machine that works under the control of stored programs to accept process
& output data/information for use by the operator.
 A device that accepts data, processes the data in accordance with a stored program,
generates results, and usually consists of input, output, storage, and arithmetic, logic, and
control units.
 A functional unit that can perform substantial computation, including numerous
arithmetic operations or logic operations, without human intervention during a run.
 It is an electronic device/machine that accepts data (raw facts & figures) as input and
processes (works on it) to produce information (data converted to meaningful form) as
output.
*NB* _The computer is made up of hardware, software and peripheral devices_
 A computer is a programmable machine designed to perform arithmetic and logical
operations automatically and sequentially on the input given by the user and gives the
desired output after processing. Computer components are divided into two major
categories namely hardware and software. Hardware is the machine itself and its
connected devices such as monitor, keyboard, mouse etc. Software are the set of
programs that make use of hardware for performing various functions.
*HARDWARE*
 Refers to the tangible, physical and mechanical components of a computer.
 The computer equipment that you need to "run" the software,
 Refers to the physical elements that make up a computer or electronic system and
everything else involved that is physically tangible.
 This includes the monitor or screen, mouse, keyboard, hard drive, memory and the CPU.
Hardware works hand-in-hand with firmware and software to make a computer function.
*SOFTWARE*
 Refers to the intangible computer components, which are the programs or instructions of
the computer.
 Is a set of instructions or programs instructing a computer to do specific tasks.
 _Software is a generic term used to describe computer programs_
 Scripts, applications, programs and a set of instructions are the terms often used to
describe software.
 Everything that a computer does, it acts under instructions written out as computer
programs.

3rmmakaha@gmail.com
 The hardware needs these instructions to function
*PROGRAM* (computer program)
 A set of instructions, written in a specific programming language, which a computer
follows in processing data, performing an operation, or solving a logical problem. _See
also software_
 A computer program is a set of statements or instructions to be used directly or indirectly
in a computer in order to bring about a certain result.
*NB* _Software alone is useless, so is the hardware. The two are inseparable_
*FIRMWARE*
 Firmware is a software program permanently etched into a hardware device such as a
keyboards, hard drive, BIOS, or video cards.
 It is programmed to give permanent instructions to communicate with other devices and
perform functions like basic input/output tasks.
 Firmware is typically stored in the flash ROM (read only memory) of a hardware device.
 It can be erased and rewritten.
_Firmware was originally designed for high level software and could be changed without
having to exchange the hardware for a newer device. Firmware also retains the basic
instructions for hardware devices that make them operative. Without firmware, a
hardware device would be non-functional_
 Originally, firmware had read-only memory (ROM) and programmable read-only
memory (PROM). It was designed to be permanent. Eventually PROM chips could be
updated and were called erasable programmable read-only memory (EPROM).
*PERIPHERAL DEVICES*
 These are devices that are external (not part of the computer) but can be connected to a
computer.
 They are not essential for the functioning of the computer but can be connected to the
computer for specific reasons.
 Examples are: _scanners, modems, printers, speakers, digital cameras, etc._
*FUNCTIONS OF A COMPUTER*
 *Input (Data)*
o The computer accepts data from outside for processing. Input is the raw
information entered into a computer from the input devices.

4rmmakaha@gmail.com
o Transferring of information into the system. This may be through a user
input device - i.e. keyboard, mouse, scanner etc.. Or though previously
loaded software/program, cd etc.
 *Processing*
o The computer performs operations on the data that it holds internally.
o Processing is the operation of data as per given instruction.
o It is totally internal process of the computer system.
o This is where the computer actually does the 'work' - manipulating and
controlling data over the entire system.
 *Output*
o The computer produces information for external use.
o Output is the processed data given by computer after data processing. Output is
also called as Result.
o Output is the exact opposite of input.
o Output is the function that allows a computer to display information, from
the system, for the user.
o This can be accomplished through the monitor (or other graphical
display), printer, speakers etc.
 *Storage*
o The computer stores data before, during and after processing.
o We can save results of processing in the storage devices for the future use.
o Most computers are able to store data both temporarily (in order to
process), but also long-term (i.e., permanently).
o Storage takes place on hard-drives or external storage devices.
 *Communication*
o The computer can send or receive data to or from other computers when it is
connected on a network

5rmmakaha@gmail.com
HARDWARE VS SOFTWARE
HARDWARE SOFTWARE
 Physical components of a computer system.
Devices that are required to store and
execute (or run) the software.
 Intangible components of a computer
system, which are programs or instructions
that enables a user to interact with the
computer.
 Input, storage, processing, control, and
output devices.
 System software, Programming software,
and Application software.
 CD-ROM, monitor, printer, video card,
scanners, label makers, routers, and
modems.
 QuickBooks, Adobe Acrobat, WhatsApp ,
Internet Explorer , Microsoft Word ,
Microsoft Excel
 Hardware serves as the delivery system for
software solutions. The hardware of a
computer is infrequently changed, in
comparison with software and data, which
are “soft” in the sense that they are readily
created, modified, or erased on the
computer
 To perform the specific task you need to
complete. Software is generally not needed
to for the hardware to perform its basic level
tasks such as turning on and responding to
input.
 Hardware starts functioning once software
is loaded.
 To deliver its set of instructions, Software is
installed on hardware.
 Hardware failure is random. Hardware does
have increasing failure at the last stage.
 Software failure is systematic. Software
does not have an increasing failure rate.
 Hardware wears out over time.
 Software does not wear out over time.
However, bugs are discovered in software as
time passes.
 Hardware is physical in nature.  Software is logical in nature.

6rmmakaha@gmail.com
HARDWARE SOFTWARE
 Physical parts of the computer are
called hardware.
 You can touch, see and feel
hardware.
 Hardware is constructed using
physical materials or components.
 Computer is hardware, which
operates under the control of a
software.
 If hardware is damaged, it is
replaced with new one.
 Hardware is not affected by
computer viruses.
 Hardware cannot be transferred
from one place to another
electronically through network.
 User cannot make new duplicate
copies of the hardware.
 A set of instructions given to the
computer is called software.
 You cannot touch and feel
software.
 Software is developed by writing
instructions in programming
language.
 The operations of computer are
controlled through software.
 If software is damaged or
corrupted, its backup copy can be
reinstalled.
 Software is affected by computer
viruses.
 Software can be transferred from
one lace to another electronically
through network.
 User can make many new
duplicate copies of the software.

7rmmakaha@gmail.com
MAJOR COMPONENTS OF A COMPUTER SYSTEM( block diagram)

8rmmakaha@gmail.com
DESCRIBE THE FUNCTIONS OF EACH COMPONENT.
*INPUT UNIT*
 It accepts (or reads) the list of instructions and data from the outside world.
 It converts these instructions and data in computer acceptable format.
 It supplies the converted instructions and data to the computer system for further
processing.
*OUTPUT UNIT*
1. It accepts the results produced by the computer which are in coded form and hence
cannot be easily understood by us.

9rmmakaha@gmail.com
2. It converts these coded results to human acceptable (readable) form.
3. It supplied the converted results to the outside world.
*REGISTERS*.
 The registers are the memory of the processor.
 All the data transfer is done through the registers in the processor to accelerate the
process.
*STORAGE UNIT*
1. All the data to be processed and the instruction required for processing (received from
input devices).
2. Intermediate results of processing.
3. Final results of processing before these results are released to an output device.
*CENTRAL PROCESSING UNIT (CPU)*
The CPU processes instructions it receives in the process of decoding data. In processing this
data, the CPU performs four basic steps:
1. Fetch Each instruction is stored in memory and has its own address. The processor takes
this address number from the program counter, which is responsible for tracking which
instructions the CPU should execute next.
2. Decode All programs to be executed are translated to into Assembly instructions.
Assembly code must be decoded into binary instructions, which are understandable to
your CPU. This step is called decoding.
3. Execute While executing instructions the CPU can do one of three things: Do
calculations with its ALU, move data from one memory location to another, or jump to a
different address.
4. Store The CPU must give feedback after executing an instruction and the output data is
written to the memory.
*ARITHMETIC AND LOGIC UNIT* (ALU)
An arithmetic logic unit (ALU) is a major component of the central processing unit of a
computer system. It does all processes related to arithmetic and logic operations that need
to be done on instruction words. In some microprocessor architectures, the ALU is
divided into the arithmetic unit (AU) and the logic unit (LU).

10rmmakaha@gmail.com
_ALUs routinely perform the following operations_
 *Logical Operations*: These include AND, OR, NOT, XOR, NOR, NAND, etc.
 *Bit-Shifting Operations*: This pertains to shifting the positions of the bits by a
certain number of places to the right or left, which is considered a multiplication
operation.
 *Arithmetic Operations*: This refers to bit addition and subtraction. Although
multiplication and division are sometimes used, these operations are more
expensive to make. Addition can be used to substitute for multiplication and
subtraction for division.
*CONTROL UNIT*
A control unit (CU) handles all processor control signals. It directs all input and output flow,
fetches code for instructions from microprograms and directs other units and models by providing
control and timing signals. A CU component is considered the processor brain because it issues
orders to just about everything and ensures correct instruction execution.
_CU functions are as follows_:
 Controls sequential instruction execution
 Interprets instructions
 Guides data flow through different computer areas
 Regulates and controls processor timing
 Sends and receives control signals from other computer devices
 Handles multiple tasks, such as fetching, decoding, execution handling and
storing results
_CUs are designed in two ways_:
 *Hardwired control*: Design is based on a fixed architecture. The CU is made
up of flip-flops, logic gates, digital circuits and encoder and decoder circuits that
are wired in a specific and fixed way. When instruction set changes are required,
wiring and circuit changes must be made. This is preferred in a reduced
instruction set computing (RISC) architecture, which only has a small number of
instructions.
 *Microprogram control*: Microprograms are stored in a special control
memory and are based on flowcharts. They are replaceable and ideal because of
their simplicity.

MAIN MEMORY VS SECONDARY MEMORY (RAM VS ROM)
MAIN MEMORY AUXILIARY OR BACKUP STORAGE
 Stores programs and data while computer is
running for current use
 Store data or programs for later
use
 Main memory is fast and limited in capacity  Slow and capacity vary
 Cannot retain information when the
computer is switched off - Volatile
 Non volatile
 Memory directly connected to the CPU - not
portable
 Portable- can be transported from
one machine to another.
 Primary storage  Secondary storage
 PROVIDES FAST ACCESS  ACCESS IS SLOW
 Temporary  Permanent
 Computer cannot do or work without  Can do or work without
PRIMARY MEMORY SECONDARY MEMORY
 The memory devices used for primary
memory are semiconductor memories
 The secondary memory devices are
magnetic and optical memories.
 The primary memory is categorized as
volatile and non-volatile memories, RAM is
the volatile memory and ROM is the non-
volatile memory
 The secondary memory is always non
volatile
 The primary memory is composed of
programs and data that are presently being
used by the micro processor
 The secondary memory is enough capable
to store huge amount of information
 The primary memories are more effective
and fast to interact with the micro processor
 The secondary memories are somewhat
slow in interacting with the microprocessor,
when compared with the primary memory.
 Primary memory is known as main memory  Secondary memory is known as additional
memory or back memory
 These memories are also called as internal
memory
 These memories are also called as external
memory
 Primary memory is temporary  The secondary memory is permanent
 Commonly used primary memory (main
memory) available in the range of 512 MB
to 8 GB RAMs.
 Generally secondary memories range
between 80 GB to 4 TB Hard Disc Drives.
 The primary memory devices are connected
to the computer through “slots”
 The secondary memory devices are
connected to the computer through Cables

CLASSIFICATION OF COMPUTERS
 *According to data handling, computers are analog, digital or hybrid*
 ANALOG COMPUTERS work on the principle of measuring, in which the
measurements obtained are translated into data. Modern analog computers usually
employ electrical parameters, such as voltages, resistances or currents, to represent the
quantities being manipulated. Such computers do not deal directly with the numbers.
They measure continuous physical magnitudes.
 DIGITAL COMPUTERS are those that operate with information, numerical or
otherwise, represented in a digital form. Such computers process data into a digital
value (in 0s and 1s). They give the results with more accuracy and at a faster rate.
 HYBRID COMPUTERS incorporate the measuring feature of an analog computer
and counting feature of a digital computer. For computational purposes, these
computers use analog components and for storage, digital memories are used.
 *According to, computers are classified as*
 *Analog Computer*
An analog computer is a form of computer that uses continuous physical
phenomena such as electrical, mechanical, or hydraulic quantities to model the
problem being solved
 *Digital Computer*
A computer that performs calculations and logical operations with quantities
represented as digits, usually in the binary number system
 *Hybrid Computer* (Analog + Digital)
A combination of computers those are capable of inputting and outputting in both
digital and analog signals. A hybrid computer system setup offers a cost effective
method of performing complex simulations.
*CLASSIFICATION ON THE BASIS OF SIZE*
Major classes or categories of computers
1. Supercomputer
2. Mainframe Computer
3. Minicomputer
4. Microcomputer

*SUPERCOMPUTER*
 The most powerful computers in terms of performance and data processing are the
Supercomputers. These are specialized and task specific computers used by large
organizations. These computers are used for research and exploration purposes, like
NASA uses supercomputers for launching space shuttles, controlling them and for
space exploration purpose.
 The supercomputers are very expensive and very large in size. It can be
accommodated in large air-conditioned rooms; some super computers can span an
entire building.
*Uses Of Supercomputers*
 Space Exploration
 Earthquake studies
 Weather Forecasting
 Nuclear weapons testing
*MAINFRAME COMPUTER*
 Although Mainframes are not as powerful as supercomputers, but certainly they are
quite expensive nonetheless, and many large firms & government organizations uses
Mainframes to run their business operations.
 The Mainframe computers can be accommodated in large air-conditioned rooms
because of its size.
 Super-computers are the fastest computers with large data storage capacity,
 Mainframes can also process & store large amount of data.
 Banks educational institutions & insurance companies use mainframe computers to
store data about their customers, students & insurance policy holders.
*MINICOMPUTER*
 Minicomputers are used by small businesses & firms.
 Minicomputers are also called as “Midrange Computers”.
 These are small machines and can be accommodated on a disk with not as processing
and data storage capabilities as super-computers & Mainframes.
 These computers are not designed for a single user.
 Individual departments of a large company or organizations use Mini-computers for
specific purposes. For example, a production department can use Mini-computers for
monitoring certain production process.
*MICROCOMPUTER*
 Desktop computers, laptops, personal digital assistant (PDA), tablets & smartphones
are all types of microcomputers.

 The micro-computers are widely used & the fastest growing computers.
 These computers are the cheapest among the other three types of computers.
 The Micro-computers are specially designed for general usage like entertainment,
education and work purposes.
 Well known manufacturers of Micro-computer are Dell, Apple, Samsung, Sony &
Toshiba.
 Desktop computers, Gaming consoles, Sound & Navigation system of a car,
Netbooks, Notebooks, PDA’s, Tablet PC’s, Smartphones, Calculators are all type of
Microcomputers.
*The main differences among the above computer types are in*:
 Processing speed,
 Memory capacity
 Number and capabilities or peripheral devices that can be attached to the
computer
 Usage.
*COMPUTER APPLICATIONS*
a) Business- for administration, payroll and accounting.
b) Government- keeping database records.
c) Education- Record keeping, accounting and training in the classroom.
d) Health- Record keeping, life-support systems.
e) Sport- fitness monitoring.
f) Art and Design- desktop Publishing, technical graphics, Computer Aided Design.
g) Homes- PCs for home accounts, games, e-mail, online shopping, home education etc.
h) Banks- Record keeping and updating, on-line Automated Teller Machines (ATMs).
i) Supermarkets- Electronic point Of Sale Machines (EPOS) – tills.
*FACTORS TO CONSIDER WHEN YOU WANT TO PURCHASE OR BUYA
COMPUTER*
1. *COST*; how much can I afford to pay for a computer? Prices of personal
computers range from a few hundred to thousands of dollars. Faster and more
feature-rich PCs are usually more expensive.
2. *AREA OF USE*; where will my new PC be used? If you will be using it only in
your home or office, a desktop computer will be suitable. However, if you will need
to take it with you, you should consider purchasing a laptop (notebook) computer.
3. *APPLICATIONS PACKAGES*; Which application packages will I run on my
computer? Make a list of applications for which you plan to use your PC. For

example, will you use your PC to prepare letters and reports? Analyze numeric and
financial data? Prepare visual presentations? Access the Internet? Listen to music?
Create and work with graphics?
4. *DURATION*; How long will I keep this computer?Try to estimate the length of
time (years) you will use your computerbefore BUYING the next one. If you expect
use your PC for several years or if you think you may later want to add new
applications, CONSIDER one that is expandable, so you can add new components,
such as a modem, printer, or add-on boards. Make sure the PC has expansion slots so
you can connect these devices to your PC.
5. *MANUFACTURER AND SELLER REPUTATION*. Check out the
manufacturers and seller’s reputations.Talk with friends, co-workers, classmates,
teachers, and others about their PCs. Ask about the performance of their PCs and get
recommendations from persons you trust. Eventually you may need to have your PC
serviced. Ideally, the vendor has a service department that can repair your PC. If not,
you may need to locate a third-party to provide this service. Reputable computer
manufactures include:
1. Hewlett-Packard 2. Apple 3. Sun Microsystems 4. Dell 5. Panasonic 6.Sony
7.Toshiba 8. Shuttle 9. IBM 10. Samsung Electronics 11. Hitachi 12. Fujitsu
Siemens
6. *WARRANTIES & GUARANTEES*
7. *PC ARCHITECTURE*. PC architecture refers to the design and construction of
the PC and its system unit, and not all architectures are the same. For example, the
architecture of an Apple Macintosh differs from that of an IBM or compatible PC.
Therefore, software written for an Apple Macintosh PC may not run on an IBM or
IBM-compatible PC. Although some users prefer a Macintosh PC, more software is
available for IBM and IBM-compatible PCs.
8. *MICROPROCESSOR SPEED*. Selecting the right microprocessor is extremely
important. Processing speed, measured in megahertz (MHz) or gigahertz (GHz), is
probably the first consideration. The higher the number of MHz or GHz, the faster
the processor will manipulate data. If speed is important, consider choosing a
microprocessor with a speed of 2 GHz or more. PCs containing microprocessors with
speeds up to 10 GHz and higher are available.
9. *MAIN MEMORY* (RAM). Main memory (RAM) is needed for the temporary
storage of programs and data while the data is being processed. Some application
software requires a considerable amount of RAM to function properly, and newer
software versions usually require more RAM than older versions. Typical PCs now
come with 2 gigabytes (GB), 5GB, or more of RAM. Make certain the PC has
sufficient RAM to run the software you will be using.

10. *SECONDARY STORAGE* (ROM). What type(s) and amounts of secondary
storage are you likely to need? Typical computers come with a floppy disk drive, cd
drive, USB port/ drive and a hard disk drive already installed. A hard disk drive
contains one or more rigid storage platters and provides for the permanent storage of
considerably more data. However, the disk itself cannot be removed from the drive.
The STORAGE CAPACITY of a hard disk is an important consideration because it
is used to store all system and application software. Typical hard disk capacities are
100, 200, 500GB or 2TB and more. Be certain the PC you are considering has
sufficient secondary capacity for your needs
11. *PORTS*. The number of ports (slots) available inside the system unit determines
the number of add-on boards that can be installed inside the system unit. For
example, you cannot connect a printer to your computer unless your computer is
equipped with an appropriate port (slot).
12. *INPUT DEVICES*. Typical input devices are a keyboard and a mouse, although
other kinds of input devices are available.
13. *OUTPUT DEVICES*. Output devices produce output in either soft copy or hard
copy form. Most PCs come with a monitor (for soft copy output), but you may have
to purchase a hard copy device, such as a printer, separately.
14. *MONITORS*.
 Resolution refers to the clarity of the text and images being displayed. Before
making a purchase, carefully evaluate the monitor’s resolution.
 Monitor size is another important consideration.
DATA PROCESSING
DATA
 Data is raw information
 a collection of facts from which conclusions may be drawn; "statistical data"
INFORMATION
 Data that has been processed to add or create meaning and hopefully knowledge
for the person who receives it. Information is the output of information systems.
 Organized data which is understood to have significance and meaning
DATA PROCESSING
Used specifically, data processing may refer to a discrete step in the information processing cycle
in which data is acquired, entered, validated, processed, stored, and output, either in response to
queries or in the form of routine reports; the processing is the step that organizes the information
in order to form the desired output. Used in a more general sense, data processing may also refer
to the act of recording or otherwise handling one or more sets of data, and is often performed with
the use of computers. The word data is commonly used to mean “information” and often suggests

large amounts of information in a standardized format. Data may consist of letters, numbers,
equations, dates, images, and other material, but does not usually include entire words.
DATA PROCESSING METHODS (CATEGORIES OF DATA PROCESSING)
Data is processed to get the required results. Different operations may be performed on
data. Therefore, data processing is defined as:
"A sequence of operations on data to convert it into useful information is called data
processing". The important operations that can be performed on data are:
 Arithmetic and logical operations on data to get required results.
 To send and receive data from one location to another.
 Classification of data.
 Arranging data into a specific order etc.
The data processing is divided into three methods/ categories or levels.
1. Manual Data Processing
In manual data processing, data is processed manually without using any machine or
tool to get required results. In manual data processing, all the calculations and logical
operations are performed manually on the data. Similarly, data is transferred manually
from one place to another. This method of data processing is very slow and errors may
occur in the output. Mostly, is processed manually in many small business firms as well
as government offices & institutions. In an educational institute, for example, marks
sheets, fee receipts, and other financial calculations (or transactions) are performed by
hand. This method is avoided as far as possible because of the very high probability of
error, labor intensive and very time consuming. This type of data processing forms the
very primitive stage when technology was not available or it was not affordable. With the
advancement in technology the dependency on manual methods has drastically
decreased.
In manual data processing, data is processed manually without using any machine or tool
to get required result. In manual data processing, all the calculations and logical
operations are manually performed on the data. Similarly, data is manually transferred
from one place to another. This method of data processing is very slow and errors may
occur in the output.
In Zimbabwe, data is still processed manually in many small business firms as well as
government offices & institutions.
In manual data processing data is processed manually. No machine or tool is used.

All the calculations on data are performed manually. This is a slow method and errors
may occur. This is an old method. It was used before the invention of calculators. But
data is still processed manually in many small shops.
Example: A book seller (a small book shop) records his daily transactions manually. He
prepares bills by pen, paper and carbon paper (no doubt, brain is the main data processor
in this case). At the end of day he will use carbon copies made on a particular date to
know how many books he sold and how much income he got.
2. Mechanical Data Processing
In mechanical data processing method, data is processed by using different devices like
typewriters, mechanical printers or other mechanical devices. This method of data
processing is faster and more accurate than manual data processing. These are faster than
the manual mode but still forms the early stages of data processing. With invention and
evolution of more complex machines with better computing power this type of processing
also started fading away. Examination boards and printing press use mechanical data
processing devices frequently.
In mechanical data processing, data is processed by using different tools like calculators
or other mechanical devices. This method of data processing is faster and more accurate
than manual data processing.
Mechanical data processing is more accurate than manual. Calculators, computer
programs and other devices are used on the data however someone still has to step in
between operations.

In mechanical data processing data is processed with the help of devices or machines.
These machines that help the people in data processing may be calculators and type
writers etc. Obviously, this method is faster easier and more accurate than manual data
processing.
Example: Book seller can use a calculator to speed up his data processing system. There
will be a less chance of errors in calculations. Bill calculations will be much more faster
with a calculator and easier too.
3. Electronic Data Processing
It is the modern technique to process data. The data is processed through computer. Data
and set of instructions are given to the computer as input and the computer automatically
processes the data according to the given set of instructions.
The computer is also known as electronic data processing machine. This method of
processing data is very fast and accurate. Now-a-days, the data is processed and analyzed
through computers. For example, the results of students are prepared through computer;
in banks accounts of customers are processed through computers etc.
It is the latest and fastest method of data processing. Data is processed with the help of
computer. First of all, data and set of instructions are given to the computer. Computer
gives output results after processing the data according to instructions. This method of
data processing is very fast and accurate. Electronic data processing is used in banks and
business firms, Government offices, colleges, schools, universities, businesses and other
institutes. Electronic data processing is being used in almost every field of life. Example:
Suppose there are 800 students in a college. There is a manual library system in this
college. If we want to know which students have not returned books since one year? We
will have to search registers for 800 students’ record. But computer can do this job within
seconds.

In short, we can say that: Electronic data processing:
i) is more fast
ii) is less time consuming
iii) can process large amounts of data easily
iv) can present information in more attractive way
v) will give 100 % error free results, if input and instructions are accurate.
Electronic data processing or EDP is the modern technique to process data. The data is
processed through computer; Data and set of instructions are given to the computer as
input and the computer automatically processes the data according to the given set of
instructions. The computer is also known as electronic data processing machine.
This method of processing data is very fast and accurate. For example, in a computerized
education environment results of students are prepared through computer; in banks,
accounts of customers are maintained (or processed) through computers etc.
A. Batch Processing
Batch Processing is a method where the information to be organized is sorted into groups
to allow for efficient and sequential processing. Online Processing is a method that
utilizes Internet connections and equipment directly attached to a computer. It is used
mainly for information recording and research. Real-Time Processing is a technique that
has the ability to respond almost immediately to various signals in order to acquire and
process information. Distributed Processing is commonly utilized by remote workstations
connected to one big central workstation or server. ATMs are good examples of this data
processing method.
B. Online Processing
This is a method that utilizes Internet connections and equipment directly attached to a
computer. This allows for the data stored in one place and being used at altogether
different place. Cloud computing can be considered as a example which uses this type of
processing. It is used mainly for information recording and research.

C. Real-Time Processing
This technique has the ability to respond almost immediately to various signals in order
to acquire and process information. These involve high maintainance andupfront cost
attributed to very advanced technology and computing power. Time saved is maximum in
this case as the output is seen in real time. For example in banking transactions
Example of real time processing
 Airline reservation systems
 Theatre (cinema) booking
 Hotel reservations
 Banking systems
 Police enquiry systems
 Chemical processing plants
 Hospitals to monitor the progress of a patient
 Missile control systems
Advantages
 Provides up-to-date information
 The information is readily available for instant decision-making
 Provides better services to users/customers.
 Fast &reliable
 Reduces circulation of hardcopies.
Disadvantages
 Require complex Os & are very expensive
 Not easy to develop
 Real time systems usually use 2 or more processors to share the workloads, which
is expensive.
 Require large communication equipment.
D. Distributed Processing
This method is commonly utilized by remote workstations connected to one big central
workstation or server. ATMs are good examples of this data processing method. All the
end machines run on a fixed software located at a particular place and makes use of
exactly same information and sets of instruction.

THE DATA PROCESSING CYCLE
Data collection
This is the first event in the cycle. This stage involves collection of data from the outside or also
from within the system. One can break this stage into three more stages, namely acquisition, data
entry and validation. Involves getting the data/facts needed for processing from the point of its
origin to the computer
.
Input
after the data has been acquired from the source, it is entered into the current system, upon which
the data is validated, so that correct results are given at the end of the cycle. The input devices are
many. The commonly used input devices are computer keyboard, bar code readers, scanners,
output from another system, etc. Data Input- the collected data is converted into machine-
readable form by an input device, and send into the machine
Processing
In this stage the computer processes the minutest details entered. This processing makes the data
entered usable. If the computer was not to process the data, it would not be of any use and it

would also be a big mess of data. For example, if the spreadsheet was not to process the data, then
the data in the spreadsheet would only be a mess of numbers. The spreadsheet is a program which
gives the data out back to the user in the usable form. The system used for processing, along with
the data entered will decide the kind of output, which the user will get. Processing is the
transformation of the input data to a more meaningful form (information) in the CPU
Output
If you have to look at the diagram of data/ information processing cycle, the step after processing
is the output stage. The processed information is now transmitted to the user. This stage can also
be further divided. After processing the data, there can be further interactive queries asked or
routine reports can be given. There are different forms in which the output can be given to the
user. There can be print report, which may be given to the user. The output can also be given in
the form of audio, video as well. In some cases, the results may only be displayed on the
computer monitor. Output is the production of the required information, which may be input in
future
Storage
After the data has been processed, along with the output to the user, the data is also stored.
Different computer storage devices can be used for the same. Some of the commonly used data
storage methods are disk storage, tertiary storage, etc. Storing the data also serves another
purpose. You will not have to repeat the entire cycle again. Often the storage is done in both
digital as well as hard copy format. At the same time, backup of the digital format is also
maintained, which can be retrieved in case of system crash.
The most important advantage of this cycle is that the information is processed quickly. At the
same time retrieving the data is an easy task as well. The processed information can further be
passed unto the next stage directly in case the need be. The necessary data is stored, which helps
in avoiding duplication of data as well as time.
ATTRIBUTES OF GOOD INFORMATION
Quality
Required
Commentary
Relevant The information obtained and used should be needed for decision-making. it
doesn't matter how interesting it is. Businesses are often criticised for producing
too much information simply because their information systems can "do it". A
good way of ensuring relevance is to closely define the objectives of any
information reports. Another way to improve relevance is to produce information
that focuses on "exceptions" - e.g. problems, high or low values, where limits have
been exceeded.
Up-to-date Information needs to be timely if it is to be actioned. For example, the manager of
a large retail business needs daily information on how stores are performing,
which products are selling well (or not) so that immediate action can be taken. To
improve the speed with which information is produced, businesses usually need to
look at upgrading or replacing their information systems.

Accurate As far as possible, information should be free from errors (e.g. the figures add up;
data is allocated to the correct categories). The users of information should be
informed whenever assumptions or estimates have been used. Accruate
information is usually a function of accurate data collection. If information needs
to be extremely accurate, then more time needs to be allocated for it to be checked.
However, businesses need to guard against trying to produce "perfect" information
- it is often more important for the information to be up-to-date than perfect.
Meet the
needs of the
User
Users of information have different needs. The managing director doesn't have
time to trawl through thick printouts of each week's production or sales listings -
he or she wants a summary of the key facts. The quality control supervisor will
want detailed information about quality testing results rather than a brief one-line
summary of how things are going. It is a good idea to encourage users to help
develop the style and format of information reporting that they require.
Easy to use
and
understand
Information should be clearly presented (e.g. use summaries, charts) and not too
long. It also needs to be communicated using an appropriate medium (e.g. email,
printed report, presentation. Businesses should also consider developing
"templates" which are used consistently throughout the organisation - so that users
get used to seeing information in a similar style.
Worth the
cost
Often forgotten. Information costs money. Data is costly to collect, analyse and
report. Information takes time to read and assimilate. All users should question
whether the information they recieve/have requested is worthwhile
Reliable Information should come from authoritative sources. It is good practice to quote
the source used - whether it be internal or external sources. If estimates or
assumptions have been applied, these should be clearly stated and explained.
1) Valid
2) Fit for use
3) Accessible
4) Cost effective
5) Understandable
6) Time
COMPUTER EQUIPMENT
INPUT DEVICES:
 Graphics Tablets
 Cameras
 Video Capture Hardware
 Trackballs
 Barcode reader
 Digital camera
 Gamepad
 Joystick
 Keyboard
 Microphone
 MIDI keyboard
 Mouse (pointing device)
 Scanner

 Webcam
 Touchpads
 Pen Input
 Microphone
 Electronic Whiteboard
 OMR
 OCR
 u) Punch card reader
 v)MICR (Magnetic Ink character reader)
 w) Magnetic Tape Drive
OUTPUT DEVICES:
 Monitor (LED, LCD, CRT etc)
 Printers (all types)
 Plotters
 Projector
 LCD Projection Panels
 Computer Output Microfilm (COM)
 Speaker(s)
 Head Phone
 Visual Display Unit
 Film Recorder
 Microfiche
BOTH INPUT–OUTPUT DEVICES:
 Modem
 Network cards/ Network adapter
 Touch Screen
 Headsets (Headset consists of Speakers and Microphone. Speaker act Output Device
and Microphone act as Input device)
 Facsimile (FAX) (It has scanner to scan the document and also have printer to Print
the document)
 Audio Cards / Sound Card
 CD-R/RW, DVD, and Blu-ray drive
 Digital camera
 Floppy diskette drive
 Hard drives
 SD Card
 USB thumb drives

INPUT DEVICES
These are some devices that feed data into the computer for processing. Some examples
include:-
1. KEYBOARD
2. MOUSE
3. TRACKBALL
4. LIGHT PEN
5. TOUCH SCREEN
6. MODEM
7. SCANNER
8. MICROPHONE
9. BAR CODE READER
10. DIGITAL CAMERA
11. VIDEO DIGITISER
12. MAGNETIC INK CHARACTER RECOGNITION (MICR)
13. MAGNETC STRIPS OR STRIPES READER
14. KEY TO DISK
15. GRAPHICS TABLET
16. OCR
17. OMR
18. VOICE RECOGNITION SYSTEM
Storage devices can be used as input devices
Following are few of the important input devices which are used in a computer:
KEYBOARD
Keyboard is the most common and very popular input device which helps in inputting
data to the computer. The layout of the keyboard is like that of traditional typewriter,
although there are some additional keys provided for performing additional functions.
Keyboards are of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or
108 keys are also available for Windows and Internet.
The keys on the keyboard are as follows:
Sr.No Keys Description

1 Typing Keys
These keys include the letter keys (A-Z) and digit keys (0-9) which
generally give same layout as that of typewriters.
2 Numeric Keypad
It is used to enter numeric data or cursor movement. Generally, it
consists of a set of 17 keys that are laid out in the same configuration
used by most adding machines and calculators.
3 Function Keys
The twelve function keys are present on the keyboard which are
arranged in a row at the top of the keyboard. Each function key has
unique meaning and is used for some specific purpose.
4 Control keys
These keys provide cursor and screen control. It includes four
directional arrow keys. Control keys also include Home, End, Insert,
Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt),
Escape(Esc).
5 Special Purpose Keys
Keyboard also contains some special purpose keys such as Enter,
Shift, Caps Lock, Num Lock, Space bar, Tab, and Print Screen.
MOUSE
Mouse is most popular pointing device. It is a very famous cursor-control device having a
small palm size box with a round ball at its base which senses the movement of mouse
and sends corresponding signals to CPU when the mouse buttons are pressed.
Generally it has two buttons called left and right button and a wheel is present between
the buttons. Mouse can be used to control the position of cursor on screen, but it cannot
be used to enter text into the computer.
Advantages
 Easy to use
 Not very expensive
 Moves the cursor faster than the arrow keys of keyboard.

JOYSTICK
Joystick is also a pointing device which is used to move cursor position on a monitor
screen. It is a stick having a spherical ball at its both lower and upper ends. The lower
spherical ball moves in a socket. The joystick can be moved in all four directions.
The function of joystick is similar to that of a mouse. It is mainly used in Computer
Aided Designing(CAD) and playing computer games.
LIGHT PEN
Light pen is a pointing device which is similar to a pen. It is used to select a displayed
menu item or draw pictures on the monitor screen. It consists of a photocell and an
optical system placed in a small tube. When the tip of a light pen is moved over the
monitor screen and pen button is pressed, its photocell sensing element detects the screen
location and sends the corresponding signal to the CPU.

TRACK BALL
Track ball is an input device that is mostly used in notebook or laptop computer, instead
of a mouse. This is a ball which is half inserted and by moving fingers on ball, pointer
can be moved. Since the whole device is not moved, a track ball requires less space than
a mouse. A track ball comes in various shapes like a ball, a button and a square.
 A trackball is a pointing device consisting of a ball held by a socket containing sensors to
detect a rotation of the ball about two axes—like an upside-down mouse with an exposed
protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to
move a pointer.
 Compared with a mouse, a trackball has no limits on effective travel; at times, a mouse can reach an edge of its working area
while the operator still wishes to move the screen pointer farther. With a trackball, the operator just continues rolling, whereas a
mouse would have to be lifted and re-positioned. Some trackballs have notably low friction, as well as being made of dense
material such as glass, so they can be spun to make them coast. The trackball's buttons may be situated to that of a mouse or to a
unique style that suits the user.
 Large trackballs are common on CAD workstations for easy precision. Before the advent of
the touchpad, small trackballs were common on portable computers, where there may be no
desk space on which to run a mouse. Some small thumb balls clip onto the side of the
keyboard and have integral buttons with the same function as mouse buttons.
SCANNER
Scanner is an input device which works more like a photocopy machine. It is used when
some information is available on a paper and it is to be transferred to the hard disc of the
computer for further manipulation. Scanner captures images from the source which are
then converted into the digital form that can be stored on the disc. These images can be
edited before they are printed.

DIGITIZER
Digitizer is an input device which converts analog information into digital form. Digitizer
can convert a signal from the television or camera into a series of numbers that could be
stored in a computer. They can be used by the computer to create a picture of whatever
the camera had been pointed at. Digitizer is also known as Tablet or Graphics Tablet
because it converts graphics and pictorial data into binary inputs. A graphic tablet as
digitizer is used for doing fine works of drawing and image manipulation applications.
MICROPHONE
Microphone is an input device to input sound that is then stored in digital form. The
microphone is used for various applications like adding sound to a multimedia
presentation or for mixing music.
MAGNETIC INK CARD READER(MICR)
MICR input device is generally used in banks because of a large number of cheques to be
processed every day. The bank's code number and cheque number are printed on the
cheques with a special type of ink that contains particles of magnetic material that are
machine readable. This reading process is called Magnetic Ink Character Recognition
(MICR). The main advantage of MICR is that it is fast and less error prone.

OPTICAL CHARACTER READER(OCR)
OCR is an input device used to read a printed text. OCR scans text optically character by
character, converts them into a machine readable code and stores the text on the system
memory.
BAR CODE READERS
Bar Code Reader is a device used for reading bar coded data (data in form of light and
dark lines). Bar coded data is generally used in labeling goods, numbering the books etc.
It may be a hand held scanner or may be embedded in a stationary scanner. Bar Code
Reader scans a bar code image, converts it into an alphanumeric value which is then fed
to the computer to which bar code reader is connected.
A barcode reader, also called a price scanner or point-of-sale ( POS ) scanner, is a hand-held or
stationary input device used to capture and read information contained in a bar code . A barcode
reader consists of a scanner , a decoder (either built-in or external), and a cable used to connect
the reader with a computer. Because a barcode reader merely captures and translates the barcode
into numbers and/or letters, the data must be sent to a computer so that a software application can
make sense of the data. Barcode scanners can be connected to a computer through a serial port ,
keyboard port , or an interface device called a wedge . A barcode reader works by directing a
beam of light across the bar code and measuring the amount of light that is reflected back. (The
dark bars on a barcode reflect less light than the white spaces between them.) The scanner
converts the light energy into electrical energy, which is then converted into data by the decoder
and forwarded to a computer.

OPTICAL MARK READER (OMR)
OMR is a special type of optical scanner used to recognize the type of mark made by pen
or pencil. It is used where one out of a few alternatives is to be selected and marked. It is
specially used for checking the answer sheets of examinations having multiple choice
questions.
Short for Optical Mark Reading or Optical Mark Recognition, OMR is the process of
gathering information from human beings by recognizing marks on a document. OMR is
accomplished by using a hardware device (scanner) that detects a reflection or limited
light transmittance on or through piece of paper.
OMR allows for the processing of hundreds or thousands of physical documents per hour.
For example, students may recall taking tests or surveys where they filled in bubbles on
paper (shown right) with pencil. Once the form had been completed, a teacher or teacher's
assistant would feed the cards into a system that grades or gathers information from them.

STYLUS
 In computing, a stylus is a pen-shaped instrument used with graphics tablets or
devices that utilize touchscreen input. It is used to write or draw on a screen,
similar to how you would on a sheet of paper. Unlike a pen, styluses have a
plastic or felt tip depending on its purpose and functionality. The picture example
shows the Palm Z22 Stylus.
Which devices use a stylus?
 Originally, the stylus was not commonly found or used with devices other than
graphics tablets and PDAs. However, with the rising popularity of touch screens
on mobile devices, many individuals like to use a stylus as a replacement for their
finger. The reasoning varies, but it's usually for more accurate navigation or to
keep oils from their fingers off of their device's screen.
PUNCH CARD
 Early method of data storage used with early computers. Punch cards also known
as Hollerith cards and IBM cards are paper cards containing several punched
holes that were punched by hand or machine to represent data. These cards
allowed companies to store and access information by entering the card into the
computer. The picture is an example of a punch card.
 Punch cards are known to be used as early as 1725 for controlling textile looms.
The cards were later used to store and search for information in 1832 by Semen
Korsakov. Later in 1890, Herman Hollerith developed a method for machines to
record and store information on punch cards to be used for the US census. He
later formed the company we know as IBM.
 Punch cards were the primary method of storing and retrieving data in the early
1900s, and began being replaced by other methods in the 1960s and today are
rarely used.

TOUCHSCREEN
 A touchscreen is a monitor or other flat surface with a sensitive panel directly on
the screen that registers the touch of a finger as an input. Instead of being touch-
sensitive, some touchscreens use beams across the screen to create a grid that
senses the presence of a finger.
 A touchscreen allows the user to interact with a device without a mouse or
keyboard and is used with smartphones, tablets, computer screens, and
information kiosks.
How do you use the touchscreen?
 Note: Not all touchscreens act the same, and any of the below actions may react
differently on your device.
 Tap - A gentle touch or tap of the screen with a finger once to open an app or
select an object.
 Double-tap - Depending on where you are a double-tap can have different
functions. For example, in a browser double-tapping the screen zooms into where
you double-tapped. Double-tapping text in a text editor selects a word or section
of words.
 Touch and hold - Gently touching and holding your finger over an object selects
or highlights the object. For example, you could touch and hold an icon and then
drag it somewhere else on the screen or highlight text.
 Drag - After you have touched and held anything on the screen while keeping the
your finger on the screen drag that object or highlight in any direction and then
lift your finger off of the screen to drop it in place or stop highlighting.
 Swipe - Swiping your finger across the screen scrolls the screen in that direction.
For example, pressing the finger at the bottom of the screen and quickly moving it
up (swiping) scrolls the screen down.
 Pinch - Placing two fingers on the screen and then pinching them together zooms
out and pinching your fingers together and then moving them away from each
other zooms into where you started.

WEBCAM
 A webcam is a hardware camera connected to a computer that allows anyone
connected to the Internet to view either still pictures or motion video of a user or
other object. The picture of the Logitech Webcam C270 is a good example of
what a webcam may look. Today, most webcams are either embedded into the
display with laptop computers or connected to the USB or FireWire port on the
computer.
 Note: Unlike a digital camera and digital camcorder, a webcam does not have any
built-in storage. Instead, it is always connected to a computer and uses the
computer hard drive as its storage.
DIGITAL CAMERA
 A digital camera is a camera that stores the pictures and video it takes in
electronic format instead of to film. The picture is of a Casio QV-R62, a 6.0 Mega
Pixel digital camera and example of a typical digital camera.
 Note: A camera that is always connected to your computer with no storage could
also be referred to as a digital camera. However, it is more appropriate to refer to
this camera as a webcam.
Digital camera advantages
 Below are key advantages that make digital cameras a popular choice when
compared to film cameras.
 LCD screen
 The LCD screen can show photos and videos after they have been taken, which
allows you to delete the photo if you do not like the results or show other people.
 Storage
 A digital camera can store hundreds of pictures instead of only up to 36 pictures.
 Picture development
 Digital camera pictures can be developed, but you can pick and choose what
pictures to develop instead of having to develop a full role of film with pictures
you don't want.
 Size
 Because a digital camera does not need a place for film a digital camera (not an
SLR) is much smaller and can easily be carried in your pocket or purse.

BIOMETRICS
 When referring to computers and security, biometrics is the identification of a
person by the measurement of their biological features. For example, a user
identifying themselves to a computer or building by their finger print or voice is
considered a biometrics identification. When compared to a password, this type of
system is much more difficult to fake since it is unique to the person. Below is a
listing of all known biometric devices.
 Other common methods of a biometrics scan are a person's face, hand, iris, and
retina.
Types of biometric devices
 Face scanner - Biometric face scanners identify a person by taking measurements
of a person face. For example, the distance between the persons chin, eyes, nose,
and mouth. These types of scanners can be very secure assuming they are smart
enough to distinguish between a picture of a person and a real person.
 Hand scanner - Like your finger print, the palm of your hand is also unique to
you. A biometric hand scanner will identify the person by the palm of their hand.
 Finger scanner - Like the picture shown on this page a biometric finger scanner
identifies the person by their finger print. These can be a secure method of
identifying a person, however, cheap and less sophisticated finger print scanners
can be duped a number of ways. For example, in the show Myth Busters they
were able to fake a finger print using a Gummy Bear candy treat.
 Retina or iris scanner - A biometric retina or iris scanner identifies a person by
scanning the iris or retina of their eyes. These scanners are more secure biometric
authentication schemes when compared to the other devices because there is no
known way to duplicate the retina or iris.
 Voice scanner - Finally, a voice analysis scanner will mathematically break down
a person's voice to identify them. These scanners can help improve security but
with some less sophisticated scanners can be bypassed using a tape recording.

PADDLE
o More commonly known as a game paddle or gamepad, a paddle is an
input device commonly used with games that may contain various buttons
used to steer and utilize different options in a game. All console game
systems utilize a paddle or gamepad for control. The picture shows an
example of a game paddle used with the Atari 2600.
o The term paddle may also be used to describe various handheld devices
that are capable of controlling a function on a computer or electronic
device.
TOUCHPAD
 Alternatively referred to as a glide pad, glide point, pressure sensitive tablet, or
trackpad, a touchpad is an inputdevice on laptops and some keyboards to move
a cursor with your finger. It can be used in place of an external mouse.
 A touchpad is operated by using your finger and dragging it across the flat surface
of the touchpad. As you move your finger on the surface, the mouse cursor moves
in that same direction. Like most computer mice, the touchpad also has two
buttons below the touch surface that allows you to left-click or right-click.

MICR
 Short for Magnetic-Ink Character Recognition, MICR is a font capable of
recognition using magnetically charged ink. Computers equipped with the right
hardware and software can print or read the character printed in such ink.
 MICR font is commonly used to print checks, deposit slips, mortgage coupons,
etc. There are several MICR fonts, the MICR E-13B font is used in the Canada,
Panama, Puerto Rico, UK, and the United States. The MICR CRC-7 was created
according to the ISO standards and is a font used in France, Mexico, Spain, and
most other Spanish speaking countries.
MAGNETIC CARD READER
 A magnetic card reader is a device that can retrieve stored information from a
magnetic card either by holding the card next to the device or swiping the card
through a slot in the device. The picture is an example of a magnetic card reader
and a good example of the type of card reader you would see at most retail stores.
LIGHT GUN
 A light gun is a pointing input device that detects light using a photodiode in the
gun barrel. When the player of the game pulls the trigger on the gun, the screen is
blanked out for a fraction of a second, which allows the photodiode to determine
where the gun is pointed. Light guns were most widely used with early console
gaming systems such as the NES Zapper light gun, as shown in the picture. Using
this gun the player could play games where they were required to point the gun at
the screen and shoot targets, such as ducks in the popular Duck Hunt game.

GRAPHICS TABLET
 Alternatively referred to as a drawing tablet and pen tablet, a graphics tablet is
a hardware input device that enables an artist to draw or sketch digitally using a
pen or stylus. They are helpful because they provide a more natural and precise
feel than a standard computer mouse. The picture to the right shows an example
of a Pen Graphics Tablet from Wacom.
 Similar to an artist drawing with a pencil and paper, a user draws on the graphics
tablet with a stylus. The computer will convert the drawing strokes into digital
form, displaying them on the computer screen.
 The graphics tablet can also be used to capture users' signatures. This use is
similar to the signature pads found at many retail stores, where you would write
your signature after using a credit card to make a purchase.
TEXT INPUT DEVICES
 Chorded keyboard ,GKOS keyboard ,Keyer ,Telegraph key
(~20 WPMMorse code)
 Vibroplex (30–80 WPM Morse) ,Keyboard, Typing ,Computer
keyboard
 Handwriting recognition ,Optical character recognition ,Speech
recognition
POINTING DEVICES
 Light pen,Light gun,Cyberglove ,Touch screen ,Head pointer
,Eye gaze/eye tracking
 Computer mouse ,Trackball ,Touchpad ,Pointing stick
,Graphics tablet (or digitizing tablet) ,Stylus
GAMING DEVICES
 paddle, Power Pad, Joystick ,Gamepad (or joypad)
IMAGE, VIDEO INPUT
DEVICES
 Digital camcorder ,Webcam, Digital video recorder,Image
scanner
 3D scanner ,Digital camera
AUDIO INPUT DEVICES
 Microphone (see also speech recognition) ,Digital audio
recorder ,Digital Dictaphone

OUTPUT DEVICES
 3D Printer
 Braille embosser
 Braille reader
 Flat panel
 GPS
 Headphones
 Computer Output Microfilm (COM)
 Monitor
 Plotter
 Printer (Dot matrix printer, Inkjet printer, and Laser printer)
 Projector
 Sound card
 Speakers
 Speech-generating device (SGD)
 TV
 Video card
 Buzzers
 Motors
 Switched outputs
 Lights
 Mechanical devices, eg a robot arm
Keep in mind that drives such as a CD-ROM, DVD, Floppy diskette drive, and USB
Flash drive may be capable of receiving information from the computer, but they are not
output devices. These are considered storage devices.
1. 3D PRINTER
 Created by Charles Hull in 1984, the 3D printer is a printing device that creates a
physical object from a digital model using materials such as metal alloys,
polymers, or plastics.
 An object's design typically begins in a computer aided design (CAD) software
system, where its blueprint is created. The blueprint is then sent from the CAD
system to the printer in a file format known as a Stereo lithography (STL), which
is typically used in CAD systems to design 3D objects. The printer then reads the
blueprint in cross-sections and begin the process of recreating the object just as it
appears in the computer aided design. In the picture below is an example of a 3D
printer called the FlashForge.

Application of 3D printers
3D printers are used in many disciplines--aerospace engineering, dentistry, archaeology,
biotechnology, and information systems are a few examples of industries that utilize
them. As an example, a 3D printer might be used in the field of archaeology to physically
reconstruct ancient artifacts that have been damaged over time, thus eliminating the
2. SPEAKER
Allows a user to hear sounds and music from the computer provided the system has
installed a sound card.
3. MODEM
An Input/ Output electronic device with circuits which changes data to be transmitted
from its machine form (digital form) into a form suitable for transmission over the
telephone line (analogue form). At the receiving end it converts data vice-versa. It is
only necessary when one needs to communicate information over a long distance and
when connected to the internet.
4. HEADPHONES
Headphones give sound output from the computer. They are similar to speakers,
except they are worn on the ears so only one person can hear the output at a time
5. SOUND CARD
 Alternatively referred to as an audio output device, sound board, or audio card.
A sound card is an expansion card or IC for producing sound on a computer that
can be heard through speakers or headphones. Although the computer does not
need a sound device to function, they are included on every machine in one form
or another, either in an expansion slot (sound card) or on the motherboard
(onboard).

Sound card connections
The picture is an example of a sound card audio ports or audio jacks on the back of
your computer, associated colors, and the connector symbols.
 Digital Out (White or Yellow; words: "Digital" or "Digital Out") - Used with
surround sound or loudspeakers.
 Sound in or line in (Blue; Arrow pointing into waves) - Connection for external
audio sources, e.g. tape recorder, record player, or CD player.
 Microphone or Mic (Pink; Microphone) - The connection for a microphone or
headphones.
 Sound out or line out (Green; Arrow pointing out of waves) - The primary sound
connection for your speakers or headphones. This sound card also has a second
(black) and third (orange) sound out connector.
 Firewire (Not pictured) - Used with some high-quality sound cards for digital
video cameras and other devices.
 MIDI or joystick (15 pin yellow connector) - Used with earlier sound cards to
connect MIDI keyboard or joystick.
Tip: Usually the cables connecting to the devices are also color-coded and will match or
be close to the colors the cables connect into. For example, the end of the speakers cable
may have a green line or be completely green.
Uses of a computer sound card
 Games
 Audio CDs and listening to music
 Watch movies
 Audio conferencing
 Creating and playing Midi
 Educational software
 Business presentations
 Record dictations
 Voice recognition

6. PLOTTERS
A plotter is a computer hardware device much like a printer that is used for
printing vector graphics. Instead of toner, plotters use a pen, pencil, marker, or
another writing tool to draw multiple, continuous lines onto paper rather than
a series of dots like a traditional printer. Though once widely used for
computer-aided design, these devices have more or less been phased out by
wide-format printers. Plotters are used to produce a hard copy of schematics
and other similar applications.
A plotter can be used to produce high quality, accurate, A3 size or bigger drawings.
They are usually used for Computer Aided Design (CAD) and Computer Aided
Manufacture (CAM) applications such as printing out plans for houses or car parts.
Plotters:
How it works:  A drum plotter prints by moving a pen sideways
over the surface of a sheet of paper.
 One high precision motor moves the pen from side
to side.
 Another high precision motor moves the paper
backwards and forwards.
 An electromagnet lifts and drops different coloured
ink pens onto the paper to draw lines.
 A flat-bed plotter uses two high precision motors, one to move the
 pen in the X direction and one to move it in the Y direction.
 The paper does not move.
Suitable uses:  Plotters are restricted to line drawing and can only create a solid
region of colour by drawing a number of close, regular lines.
 Plotters are often used in science and engineering applications for
drawing building plans, printed circuit boards and machine parts.
Advantages:  They are accurate and can produce far larger printouts than
standard printers.

Disadvantages:  Slow and relatively expensive compared to printers.
 They cannot print raster (photographic) images.
 They can only fill solid blocks of colour using closely hatched lines.
7. SPEAKER
A speaker gives you sound output from your computer. Some speakers are built
into the computer and some are separate
8. BRAILLE READER
 A braille reader, also called a braille display, is an electronic device that allows
a blind person to read the text displayed on a computer monitor. The computer
sends the text to the output device, where it is converted to Braille and
"displayed" by raising rounded pins through a flat surface on the machine.
 Braille readers come in various forms, including large units (about the size of a
computer keyboard) and smaller units, designed to work with laptops and tablet
computers. There are also Braille reader apps for smartphones and tablets that
work in conjunction with a Bluetooth-connected Braille output device.
9. VIDEO CARD
Alternatively known as a display adapter, graphics card, video adapter, video board,
or video controller, a video card is an IC or internal board that creates a picture on a
display.

Video card ports
The picture above is an example of a video card with three connections, or video ports,
on the back.
 VGA connector
 S-Video connector
 DVI connector
In the past, VGA or SVGA was the most popular connection used with computer
monitors. Today, most flat panel displays use the DVI connector or HDMI connector (not
pictured above).
Video card expansion slots
 In the picture above, the video card is inserted into the AGP expansion slot on the
computer motherboard. Over the development of computers, there have been
several types of expansion slots used for video cards. Today, the most common
expansion slot for video cards is PCIe, which replaced AGP, which replaced PCI,
which replaced ISA.
10. GPS
 Short for Global Positioning System, GPS is a network of satellites that
helps users determine a location on Earth. The thought of GPS was conceived
after the launch of Sputnik in 1957. In 1964, the TRANSIT system became
operational on U.S. Polaris submarines and allowed for accurate positioning
updates. Later this became available for commercial use in 1967. The picture
shows an example of the GARMIN nuvi 350, a GPS used to find locations
while driving.
 On September 1, 1983 Soviet jets shot down a civilian Korean Air Lines
Flight 007 flying from New York to Seoul and kill all 269 passengers and
crew. As a result of this mistake, President Ronald Regan orders the U.S.
military to make Global Positioning System (GPS) available for civilian use.
 Today, with the right equipment or software, anyone can establish a
connection to these satellites to establish his or her location within 50 to 100
feet.

11. PROJECTOR
 A projector is an output device that can take images generated by a computer and
reproduce them on a large, flat (usually lightly colored) surface. For example,
projectors are used in meetings to help ensure that all participants can view the
information being presented. The picture is that of a ViewSonic projector.
12. VDU (Visual Display Unit)
 The VDU is output device. It displays images and text in colour or black and white as it.
It displays results of processing. It is also called a monitor.
 The VDU serves as a graphical interface between the user and the computer. it
allows the user to see what he or she is doing in a comprehensive manner.
Flat-panel display
 Sometimes abbreviated as FPD, a flat-panel display is a thin screen display
found on all portable computers and is the new standard for desktop computers.
Unlike (CRT) monitors, flat-panel displays use liquid-crystal display (LCD) or
light-emitting diode (LED) technology to make them much lighter and thinner
compared to a traditional monitor. The picture shows an example of an ASUS
flat-panel display.
13. PRINTERS
It produces output on paper i.e. hard copy or on other print-key media. The 2 types of
printers are impact and non-impact.
Impact printers
The printing device being a series of pins have a direct impact on the paper. The pins form
characters on the paper by pressing a printing element and an inked ribbon against paper. An

example of such a printer is the Dot Matrix. The printers are reasonably fast, inexpensive and can
produce both text and graphics. They also accommodate various paper sizes but are however
noisy.
Non-impact printers
These are quieter printers and examples include LaserJet and inkjet printers. The Laser printers
are a more popular choice for business use. They use a printing technique similar to that used in a
photocopying machine. A laser beam is used to form an image onto the paper using toner. The
print quality is high. Lasers are fast, and quiet. They print graphics but are more expensive.
The ink-jet printers are mainly colour printers which mix ink depending on the image colour and
spray it onto the paper. The toner has the 4 basic colours. They are slow, expensive and have a
high print quality.
What is the difference between impact and non-impact printers?
DIFFERENCES BETWEEN IMPACT AND NON-IMPACT PRINTERS
IMPACT PRINTERS NON-IMPACT PRINTERS
1
 It produces print on paper by striking
mechanism.
 It produces print on paper with a non-striking
mechanism
2
 It uses pins, hammers or wheel to strike
against an inked ribbon to print on a paper..
 It uses laser, spray of special ink, or heat and
pressure to print on paper.
3
 Normally impact printers use continuous
paper sheet.
 Non-Impact printers normally use individual
paper sheets.
4  Impact printers are normally less expensive.  Non-Impact printers are more expensive.
5
 Print quality of impact printers is lower than
those of non-impact printers..
 Print quality of Non-Impact printers is higher
than those of impact printers.
6
 Impact printers use special inked ribbons to
produce print on paper when print head
strikes.
 Non-Impact printers use toner or cartridge for
printing on paper.
7
 Impact printers are low speed printers. They
consume a lot of time to print a document.
 Non-Impact printers are very fast, they can print
many pages per minute.
8
 Impact printers are very noisy because they
strike print head.
 Non-Impact printers do not make a noise
because they do not use striking mechanism in
which print head strikes on ribbon and paper etc.
9
 Examples of Impact printers are Dot matrix
and daisy wheel printers.
 Examples of Non-Impact printers are laser
printers and inkjet printers.
10
 Impact printers use old printing
technologies.
 Non-impact printers use latest printing
technologies.
Give two advantages of non-impact printers over impact printers.
 Have high print quality
 They are fast and do not make noise

 They are reliable because they have less moving parts
 See above [non impact section]
Give three examples of impact printers &three examples of non-impact printers.
Impact printers Non impact printers
Dot matrix Laser
Daisy wheel printers Inkjet
Line printers LED
Chain printers Thermal
Magnetic
Electrostatic
Xerographic
NON-IMPACT PRINTERS
1 - LASER PRINTERS:
How it works:  These print individual pages and work in a
similar way to photocopiers.
 A drum is charged to match the image and
powdered ink (toner) sticks to the
surface. The toner is then transferred to the
paper and fixed by heat and pressure.
 A school or business printer would have a
typical speed of 10 to 20 pages per minute
(ppm).
Suitable uses:  Common wherever fast, high quality printing is required.
Disadvantages:  Non-colour laser printers are more expensive than ink-jet printers
(but the difference is narrowing).
 Colour laser printers are considerably more expensive. (but their speed
and high quality output means they are becoming more popular).
Advantages:  They are quiet and fast and produce high quality printouts.
 Running cost are low because although toner cartridges are expensive
to replace, they last a long time.
A type of printer that utilizes a laser beam to produce an image on a drum. The light of the laser
alters the electrical charge on the drum wherever it hits. The drum is then rolled through a
reservoir of toner, which is picked up by the charged portions of the drum. Finally, the toner is
transferred to the paper through a combination of heat and pressure

2 - INK-JET PRINTERS:
How it works:  The print head contains tiny nozzles
through which different coloured inks can
be sprayed onto the paper to form the
characters or the graphic images.
 The ink is forced out by heat or by tiny
piezoelectric crystals which change shape
when an electric current is applied across
them.
Suitable uses:  A popular choice for home use where small amounts of printing are
done and photographic quality colour printing is needed.
Disadvantages:  The ink cartridges can be expensive so running costs can be high.
 The printing speed is slow compared to a laser printer.
Advantages:  These printers are relatively inexpensive and produce high quality
black and white or photographic quality borderless colour printing.
A type of printer that works by spraying ionized ink at a sheet of paper. Magnetized plates in the
ink's path direct the ink onto the paper in the desired shapes. Ink-jet printersare capable of
producing high quality print approaching that produced by laser printers
3. Thermal transfer printers- A type of printer that applies heat to a ribbon and the
image or barcode is then transferred to labels or tags. This technology produces a higher quality,
longer lasting image on the tag or label.
Advantages
-1 to 2 years media shelf life
-Media is not heat sensitive
-Medium to high image quality
-Wide range of available types
-Recommended for industrial use
Disadvantages
-Special ribbons required
-Average operational cost
-Cannot print on multiple-copy paper
-Single-pass ribbons only
4. Direct thermal printers - A type of printer that applies heat directly to specially
treated paper, labels or tags to form the image or barcode.
Advantages
-No ribbon required
-Low operational cost
Disadvantages
-Short media shelf life
-Very heat sensitive media
-Limited image quality
-Limited number of available types

-Not recommended for use in industrial, outdoor, or harsh environments
-Cannot print on multiple-copy paper
IMPACT PRINTERS
1 - DOT MATRIX PRINTERS:
How it works:
The print head
travels from side to
side across the paper
and is made up of
numerous pins
which are pushed out
to form the shape of each character
The pins hit an ink ribbon against the paper
so the characters are printed out.
The paper is usually continuous with holes
down each side and perforations so the pages
can be easily separated by tearing.
Because the pins make an impact against the
paper the characters can be printed through
several layers of self-carbonating paper to
produce duplicate copies.
Suitable uses:  Limited to situations where duplicate copies are needed and the quality
is not too important.
 Typical uses might be in warehouses where duplicate copies of orders
need to produced quickly and cheaply.
Disadvantages
:
 The printing quality is low - these printers produce low to medium
quality black and white printing and can only print low resolution
graphics.
 Because of the impact of the pins against the paper, these printers can be
quite noisy.
Advantages:  The purchase cost is low and the running costs are very low.
 They can print fairly quickly, particularly if you remember that
multiple copies are being printed in one print run.
 They are robust and can operate in harsh environments.
 If several sheets of self-carbonating paper are placed into the printer
then the impact will produce duplicate copies.
A type of printer that produces characters and illustrations by striking pins against an ink ribbon
to print closely spaced dots in the appropriate shape.

Advantages
-Can print to multi-page forms-
-Moderately priced
-Multi-pass ribbons (saves money)
Disadvantages
-Noisy operation
-Low-quality output
-Slow print speed
-Multi-pass ribbons (decrease in quality with each pass)
2. DAISY WHEEL PRINTERS
Head is lying on a wheel and pins corresponding to characters are like petals of Daisy
(flower name) that is why it is called Daisy Wheel Printer. These printers are generally
used for word-processing in offices which require a few letters to be sent here and there
with very nice quality.
Advantages
 More reliable than DMP
 Better quality
 The fonts of character can be easily changed
Disadvantages
 Slower than DMP
 Noisy
 More expensive than DMP

3. LINE PRINTERS
Line printers are the printers which print one line at a time.
These are of further two types
 Drum Printer
 Chain Printer
4. DRUM PRINTER
This printer is like a drum in shape so it is called drum printer. The surface of drum is
divided into number of tracks. Total tracks are equal to size of paper i.e. for a paper width
of 132 characters, drum will have 132 tracks. A character set is embossed on track. The
different character sets available in the market are 48 character set, 64 and 96 characters
set. One rotation of drum prints one line. Drum printers are fast in speed and can print
300 to 2000 lines per minute.
Advantages
 Very high speed
Disadvantages
 Very expensive
 Characters fonts cannot be changed
5. CHAIN PRINTER
In this printer, chain of character sets are used so it is called Chain Printer. A standard
character set may have 48, 64, or 96 characters.
Advantages
 Character fonts can easily be changed.
 Different languages can be used with the same printer.
Disadvantages
 Noisy

Features or factors to consider when you want to buy a printer
1. Print quality, for example the print from dot matrix printers varies with the number
of pins and even the best are inferior to laser printers.
2. Character formation, whether made from dots as in matrix printer, or full characters
as with daisywheel or laser printer
3. Multi-part, i.e. whether several copies can be printed at once, as with an impact
printer.
4. Fonts or type style; early computer users were satisfied with any quality whatsoever,
but the advances into areas such as word processing and desk top publishing have
stimulated a demand for varying typefaces or fonts within the same document
5. Letter quality, whether the quality is equivalent or superior to that of a good
typewriter and so acceptable for the word processing of mail. Some printers have a
choice of two print modes, draft quality and letter quality.
6. Speed, in terms of characters per second.
7. Graphics capabilities.
8. Flexibility, for example is it suitable for one task only, such as good letter quality but
not graphics, as with daisywheel printers, or good graphics but slow speed and
indifferent letter quality, as with some dot matrix printers.
9. Sheet feeding, in terms of single sheets, friction feed or sprocket feed.
10. Capital cost or what it costs to buy.
11. Running cost or what it costs in ribbons, print toner, special stationery &
maintenance.
12. Compatibility with standard packages; many programs support a range of printers by
generating the correct control characters for fonts, features like italics and underline,
and for graphics.
13. Robustness; some very cheap printers are ideal at home but would not last very long
in an office.
14. Reputation of the manufacturer as a supplier of printers.
You have been delegated the task of selecting a new printer from a range of different
options currently on the market. The machine has to serve a small network of
microcomputers in your office. Software used includes a word processing package,
database, spreadsheet, and presentation packages. Assuming that cost is not a major
constraint, list 10 features of the printers, which you would investigate in your evaluation.

INPUT/ OUTPUT DEVICES (IO Devices)
Alternatively referred to as an IO device, an input/output device is any hardware used
by a human operator or other systems to communicate with a computer. As the name
suggests, input/output devices are capable of sending data (input) to a computer and
receiving data from a computer (output).
Examples of input/output devices
1. CD-R/RW, DVD, and Blu-ray drive
2. Digital camera
3. Floppy diskette drive
4. Hard drives
5. Modem
6. Network adapter
7. SD Card
8. Touch screen
9. USB thumb drives
10. Headsets (Headset consists of Speakers and Microphone. Speaker act Output Device and Microphone act as Input
device)
11. Facsimile (FAX) (It has scanner to scan the document and also have printer to Print the document)
STORAGE DEVICES
Alternatively referred to as digital storage, storage, storage media, or storage medium,
a storage device is any hardware capable of holding information either temporarily or
permanently.
There are two types of storage devices used with computers: a primary storage device,
such as RAM, and a secondary storage device, like a hard drive. Secondary storage can
be removable, internal, or external storage.
Without a storage device, your computer would not be able to save any settings or
information and would be considered a dumb terminal.

Examples of computer storage
MAGNETIC STORAGE DEVICES
Today, magnetic storage is one of the most common types of storage used with
computers and is the technology that many computer hard drives use.
 Floppy diskette
 Hard drive
 SuperDisk
 Tape cassette
 Zip diskette
OPTICAL STORAGE DEVICES
Another common storage is optical storage, which uses lasers and lights as its method of
reading and writing data.
 Blu-Ray disc
 CD-ROM disc
 CD-R and CD-RW disc
 DVD-R, DVD+R, DVD-RW, and DVD+RW disc

FLASH MEMORY DEVICES
Flash memory has started to replace magnetic media as it becomes cheaper as it is the
more efficient and reliable solution.
 Jump drive or flash drive
 Memory card
 Memory stick
 SSD
ONLINE AND CLOUD
Storing data online and in cloud storage is becoming popular as people need to access
their data from more than one device.
 Network storage
 Google drive
 SkyDrive now OneDrive
 iCloud
 email storage
 mediafire.com

PAPER STORAGE
Early computers had no method of using any of the above technologies for storing
information and had to rely on paper. Today, these forms of storage are rarely used or
found.
 OMR
 Punch card
When saving anything on a computer, it may ask you for a storage location, which is the
area in which you would like to save the information. By default, most information is
saved to your computer hard drive. If you want to move the information to another
computer, save it to a removable storage device such as a flash drive.
These are devices that store information permanently. They are also known as Auxiliary
storage devices or Secondary storage devices. They include:-
a) THE HARD DISK
A fixed device for storing information within the computer system unit. The disk is not
moveable and is also referred to as the C: drive. The amount of disk space a computer
has determines the power of a computer. It provides fast access known as Random access
and has high-speed storage.
b) FLOPPY DISKETTE
An external form of storage used for back up. Information can be deleted and rewritten
and re-saved. The storage device is common for microcomputers. The disks are either
High density or double density disks because data is stored more densely/ compactly than
on regular density disks. Common size of disk is 31
/2inches.
ADVANTAGES OF FLOPPY DISKETTES
1. They are cheaper than Hard disks and CD-ROMS
2. They are portable hence used to transfer data or information from one computer to
another
3. They offer direct access and they are faster than magnetic tapes
DISADVANTAGES OF FLOPPY DISKETTES

1. They are prone to viruses
2. They are difficult to handle
3. They can easily be corrupted
4. They have a relatively short life span
5. They hold relatively small amounts of data
6. They are not always 100% reliable
CARE AND HANDLING OF A FLOPPY DISKETTE
1. Don’t put the diskette near any magnetic field.
2. Don’t put the diskette near any electronic motor.
3. Don’t expose the diskette to direct sunshine or heat.
4. Store the diskette in a cool dry dust-free environment.
5. Don’t spill liquid onto the diskette.
6. Don’t use any diskette which has had liquids spilled on it.
7. Don’t bend or fold a diskette.
8. Don’t staple labels onto the diskette.
9. Use a soft pencil or felt-tip pen when writing on diskette labels, as the pressure of a
ballpoint may leave indentations on the magnetic surface.
10. Don’t touch the magnetic surface (the black plastic like plate) of the disk, as your
fingerprints may hinder the drive in reading from and writing to the disk .
c) CATRIDGE TAPE
Data is recorded in the form of magnetized spots on an iron oxide coating of a plastic
tape. Gaps are used to separate individual data records. The tape is similar to audiotapes.
Access of information from the tape is in sequential form and thus slow.
d) CD-ROM (Compact Disk Read Only Memory)
Beams of laser light are used to write on optical disks by magnetic means. After writing,
the disk can only be read from and not written to. Access to information is direct and very
fast.
e) WORM (Write Once, Read Many)
WORM Disks allow microcomputers with the proper drive known as a CD Rewriters (or
a burner) to record own data on a blank CD. Once the recording is done, the disk can only
be read from and cannot be rewritten.
Erasable optical disks are also available and are known as EPROM. The major advantage
of optical disks is their storage capacity. The information on one optical requires multiple
floppies.
f) DVD (Digital Versatile Disks)
A form of optical disks similar to CD ROMS but has much more storage
capacities of up to 3.9GB. They support audio and video as well as
data on the same disk.
g) ZIP DISKS
These are high capacity removable diskettes. They have gained favor for back-up
purposes. Some zip disks use magnetic technology and others use laser. They have a
capacity of about 100MB.
Storage devices differ in terms of capacity, cost and access methods. For any device to be
used there is a need for the device drive on the computer e.g. A floppy disk drive.

Flash memory / solid state memory
Flash memory is a non-volatile, solid state storage device.(i.e. keeps its data without power and
has no moving parts).
Flash memory is increasingly being used in a wide range of devices. Some examples include:
 Small, lightweight USB memory sticks, available for many Gigabytes.
 Memory cards for digital cameras.
 Main internal storage for tablet computers (SSD)
 Digital audio players.
 Mobile phones.
 Video game hardware.
 Flash memory offers very fast access to data and programs. However, retrieving data from an
external flash memory device such as a USB stick would be slower than an internal hard disk
because the speed of access is restricted by the USB link or connection.
 With the development of tablet computers, flash memory is used as the main form of internal
storage because there is no room for a traditional hard disk. These disks are called SSD (solid
state storage). In this case, access to the data stored in flash memory would be much faster
than from a hard disk because there are no moving parts involved.
 Currently, the down side to using flash memory as the main storage method is that it has a
limited number of read/write cycles which limits its useful life span.
 Flash memory, when packaged in a "memory card", is very resilient to damage, unlike many
other storage devices. It can withstand extremes of temperature, being immersed in water or
being accidentally dropped.
PROPERTIES OF FLASH MEMORY DEVICES
PROPERTY NOTES
Type of storage Solid state
Data access Direct access
Cost of storage
More expensive per byte of storage than hard disk, magnetic tape, CDs
and DVDs
Capacity 2 gigabytes upwards.
Speed
As an external storage device, it is slower than an internal hard disk. It is
faster than magnetic tape, CDs and DVDs.
If it is used as internal storage, it then becomes faster than an internal
hard disk.
Portability Very portable as it is designed to be fitted into small electronic devices.
Durability
Very durable. Resistant to pressure, temperature extremes and accidental
damage.
It has a limited number of read/write cycles which limits its useful life
The part of a USB stick which is inserted into the USB port can be
snapped off or damaged rendering the device unusable.
Reliability Usually very reliable.
DISK CARE
1) Do not expose them to sun or a hot environment.
2) Keep them away from moisture or water.

3) Keep them away from magnetic fields i.e. Phones, tops of some monitors, magnetized
items etc..
4) Do not touch the actual tape.
5) Keep them away from dust.
6) Do not place heavy objects on them.
7) Write on a floppy disk label only with a felt-tip pen, or write before sticking the label
8) Avoid using rubber bands, paper clips and erasers on floppy disks
HARDWARE CARE
1) Make sure there is enough space for the machines to breathe. (Fresh air is necessary
to make the fan keep the electronics cool).
2) Do not block air vents with books.
3) Keep the computer dry.
4) House the machine in a dust free environment e.g. 1ST
floor carpeted-room (Carpets
suck dust) and, use a vacuum cleaner to clean the carpet. (Dust is the biggest killer of
hard drives).
5) Do not expose the machine to extreme temperatures.
6) Properly shut down the machine before turn-off.
7) Pull the plug out of socket when there is thunder and lightning.
8) Do not move the system when the computer is on. The hard drive can be damaged.
9) Use of UPS- Uninterruptible Power Supply in case of power failures,
10) Use of Surge Protectors against too high voltages.
TYPES OF MEMORY
COMPUTER – MEMORY
A memory is just like a human brain. It is used to store data and instructions. Computer memory
is the storage space in computer where data is to be processed and instructions required for
processing are stored. The memory is divided into large number of small parts called cells. Each
location or cell has a unique address which varies from zero to memory size minus one. For
example if computer has 64k words, then this memory unit has 64 * 1024=65536 memory
locations. The address of these locations varies from 0 to 65535.
Memory is primarily of three types
 Cache Memory
 Primary Memory/Main Memory
 Secondary Memory
CACHE MEMORY
Cache memory is a very high speed semiconductor memory which can speed up CPU. It acts as a
buffer between the CPU and main memory. It is used to hold those parts of data and program
which are most frequently used by CPU. The parts of data and programs are transferred from disk
to cache memory by operating system, from where CPU can access them.
Advantages

The advantages of cache memory are as follows:
 Cache memory is faster than main memory.
 It consumes less access time as compared to main memory.
 It stores the program that can be executed within a short period of time.
 It stores data for temporary use.
Disadvantages
The disadvantages of cache memory are as follows:
 Cache memory has limited capacity.
 It is very expensive.
PRIMARY MEMORY (MAIN MEMORY)
Primary memory holds only those data and instructions on which computer is currently working.
It has limited capacity and data is lost when power is switched off. It is generally made up of
semiconductor device. These memories are not as fast as registers. The data and instruction
required to be processed reside in main memory. It is divided into two subcategories RAM and
ROM.
Characteristics of Main Memory
 These are semiconductor memories
 It is known as main memory.
 Usually volatile memory.
 Data is lost in case power is switched off.
 It is working memory of the computer.
 Faster than secondary memories.

 A computer cannot run without primary memory.
SECONDARY MEMORY
This type of memory is also known as external memory or non-volatile. It is slower than main
memory. These are used for storing data/Information permanently. CPU directly does not access
these memories instead they are accessed via input-output routines. Contents of secondary
memories are first transferred to main memory, and then CPU can access it. For example : disk,
CD-ROM, DVD etc.
Characteristic of Secondary Memory
 These are magnetic and optical memories
 It is known as backup memory.
 It is non-volatile memory.
 Data is permanently stored even if power is switched off.
 It is used for storage of data in a computer.
 Computer may run without secondary memory.
 Slower than primary memories.
RANDOM ACCESS MEMORY
RAM(Random Access Memory) is the internal memory of the CPU for storing data, program and
program result. It is read/write memory which stores data until the machine is working. As soon
as the machine is switched off, data is erased.
Access time in RAM is independent of the address that is, each storage location inside the
memory is as easy to reach as other locations and takes the same amount of time. Data in the
RAM can be accessed randomly but it is very expensive.
RAM is volatile, i.e. data stored in it is lost when we switch off the computer or if there is a
power failure. Hence a backup uninterruptible power system(UPS) is often used with computers.
RAM is small, both in terms of its physical size and in the amount of data it can hold.
RAM is of two types
 Static RAM (SRAM)
 Dynamic RAM (DRAM)

Static RAM (SRAM)
The word static indicates that the memory retains its contents as long as power is being supplied.
However, data is lost when the power gets down due to volatile nature. SRAM chips use a matrix
of 6-transistors and no capacitors. Transistors do not require power to prevent leakage, so SRAM
need not have to be refreshed on a regular basis.
Because of the extra space in the matrix, SRAM uses more chips than DRAM for the same
amount of storage space, thus making the manufacturing costs higher. So SRAM is used as cache
memory and has very fast access.
Characteristic of the Static RAM
 It has long life
 There is no need to refresh
 Faster
 Used as cache memory
 Large size
 Expensive
 High power consumption
Dynamic RAM (DRAM)
DRAM, unlike SRAM, must be continually refreshed in order to maintain the data. This is done
by placing the memory on a refresh circuit that rewrites the data several hundred times per
second. DRAM is used for most system memory because it is cheap and small. All DRAMs are
made up of memory cells which are composed of one capacitor and one transistor.
Characteristics of the Dynamic RAM
 It has short data lifetime
 Need to be refreshed continuously
 Slower as compared to SRAM
 Used as RAM
 Lesser in size
 Less expensive

 Less power consumption
READ ONLY MEMORY
ROM stands for Read Only Memory. The memory from which we can only read but cannot write
on it. This type of memory is non-volatile. The information is stored permanently in such
memories during manufacture. A ROM, stores such instructions that are required to start a
computer. This operation is referred to as bootstrap. ROM chips are not only used in the computer
but also in other electronic items like washing machine and microwave oven.
Following are the various types of ROM
MROM (Masked ROM)
The very first ROMs were hard-wired devices that contained a pre-programmed set of data or
instructions. These kind of ROMs are known as masked ROMs which are inexpensive.
PROM (Programmable Read only Memory)

PROM is read-only memory that can be modified only once by a user. The user buys a blank
PROM and enters the desired contents using a PROM program. Inside the PROM chip there are
small fuses which are burnt open during programming. It can be programmed only once and is
not erasable.
EPROM(Erasable and Programmable Read Only Memory)
The EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes.
Usually, an EPROM eraser achieves this function. During programming, an electrical charge is
trapped in an insulated gate region. The charge is retained for more than ten years because the
charge has no leakage path. For erasing this charge, ultra-violet light is passed through a quartz
crystal window(lid). This exposure to ultra-violet light dissipates the charge. During normal use
the quartz lid is sealed with a sticker.
EEPROM(Electrically Erasable and Programmable Read Only Memory)
The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about
ten thousand times. Both erasing and programming take about 4 to 10 ms (milli second). In
EEPROM, any location can be selectively erased and programmed. EEPROMs can be erased one
byte at a time, rather than erasing the entire chip. Hence, the process of re-programming is
flexible but slow.
Advantages of ROM
The advantages of ROM are as follows:
 Non-volatile in nature
 These cannot be accidentally changed
 Cheaper than RAMs
 Easy to test
 More reliable than RAMs
 These are static and do not require refreshing
 Its contents are always known and can be verified
COMPUTER - MEMORY UNITS
Memory unit is:
 The amount of data that can be stored in the storage unit.
 That in which storage capacity is expressed in terms of Bytes.
Following are the main memory storage units:
Sr.No. Unit Description
1 Bit (Binary Digit)
A binary digit is logical 0 and 1 representing a passive or an active state of a component in an
electric circuit.
2 Nibble A group of 4 bits is called nibble.
3 Byte
A group of 8 bits is called byte. A byte is the smallest unit which can represent a data item or a
character.
4 Word
A computer word, like a byte, is a group of fixed number of bits processed as a unit which
varies from computer to computer but is fixed for each computer. The length of a computer
word is called word-size or word length and it may be as small as 8 bits or may be as long as
96 bits. A computer stores the information in the form of computer words.

Few higher storage units are following………..
Sr.No. Unit Description
1 Kilobyte (KB) 1 KB = 1024 Bytes
2 Megabyte (MB) 1 MB = 1024 KB
3 GigaByte (GB) 1 GB = 1024 MB
4 TeraByte (TB 1 TB = 1024 GB
5 PetaByte (PB) 1 PB = 1024 TB
Differentiate between Random Access Memory (RAM) and Read Only Memory
(ROM)
RAM ROM
 Stands for Random-Access Memory  Stands for Read-Only Memory
 RAM is a read and write memory
 Normally ROM is read only memory and it cannot be
overwritten. However, EPROMs can be reprogrammed
 RAM is faster  ROM is relatively slower than RAM
 RAM is a volatile memory. It means
that the data in RAM will be lost if
power supply is cut-off
 ROM is permanent memory. Data in ROM will stay as it
is even if we remove the power-supply
 There are mainly two types of RAM;
static RAM and Dynamic RAM
 There are several types of ROM; Erasable ROM,
Programmable ROM, EPROM etc.
 RAM stores all the applications and
data when the computer is up and
running
 ROM usually stores instructions that are required for
starting (booting) the computer
 Price of RAM is comparatively high  ROM chips are comparatively cheaper
 RAM chips are bigger in size  ROM chips are smaller in size
 Processor can directly access the
content of RAM
 Content of ROM are usually first transferred to RAM and
then accessed by processor. This is done in order to be
able to access ROM content at a faster speed.
 RAM is often installed with large
storage.
 Storage capacity of ROM installed in a computer is much
lesser than RAM
BENEFITS OF COMPUTERS
With the advent of new technology, various processes have been very dependent with
automation. As the years go by, more and more inventions are introduced in the market
and in the society all for one purpose - convenience. Let us tackle for instance two of the
most influential aspects of this modern world; the societal and the entrepreneurial feature.
These two have been greatly influenced by the advancements that are continuously taking
place. With that said, a number of essential advantages are becoming more evident in
these two facets. To further draw a clearer picture on the benefits of computers on each of
the mentioned aspect, here are brief descriptions of each.

ADVANTAGES OF COMPUTERS
1. Data Storage: Many small businesses keep and store important business documents
on their computers. Since these computers have big storage hard-drives, they can be in
position to store millions of files and the discovery or retrieval of these files is very easy.
Data can be stored in specific folders to make it easy to access, and some data can be
made private by use of password protected folders. For medium size growing companies,
they invest in a centralized powerful computers which store all business data, this data
can be accessed via an internal or external network with in the company. This all process
creates efficiency within a business and it also helps in the transfer of data and
information from one department to another.
2. Education: Many companies use computers as a training tool at work. Due the
increased advancement in technology and business trends, it is very important for a
business to train their employees new skills. So for a business to save money in this
process of training employees, computers can be used to educate and update their
employees. However, to save time, business owners or human resource managers can use
virtual technologies to communicate and train their staff; this means that employees will
stay in their departments and on their desks as they attend a lesson. Virtual
communication software like SKYPEcan be used to train employees virtually, all you
have to do is to create a GROUP and add all your employees in that group, so you will
talk to them at once and they can also ask you questions via their computers.
3. Research: It is very difficult for a business to survive in today’s competitive business
world. For any business to succeed and gain a certain degree of competitive advantage in
any market, they have to carry out extensive research about that target market and their
competitors. It is very important to know what your competitors are doing, this
information can help you strategize your business and look unique in the eyes of the
consumer. A computer can be used to make business research on the internet, the power
of the internet is unmeasurable, because search engines like GOOGLE will give you
insights in each and every market and company. Online analytical companies like
Compete.com will help you measure your competitors’ strength online and this will help
you make wise business decision basing on facts and figures.
4. Accounting: Since accounts deals with facts and figures, it is very essential to use a
computer during the accounting process, this reduces on human errors and it also helps
business owners keep track of their businesses without any need of learning accounting
basics. Computers make accounting look too simple, so any one can use programs like
QuickBooks to balance and track inventory. Mobile computers like tablets and notebooks
can be used to access accounting data remotely. Online QuickBooks software from
companies like intuit.com can automate the invoicing process, billing and reporting
which creates efficiency in a business.

5. Marketing: A business can use a computer to create a business website. Today, it is
very easy to create a website, if your budget is limited and you can’t afford a website
designer, all you have to do is to pay for cheap hosting of around $4 per month, register
your companies domain name for only $10 per year, then install WordPress on your
domain. To create a beautiful company website, go to Themeforest.com and buy a
business WordPress theme for only $45 then install that theme on your default
WordPress site, then start editing the theme to fit your company goals, the all process is
simple and cheap. You can use your website to market your services and products, reach
more customers by integrating your website content with social media sites like facebook
and twitter.
6. Creating and Editing of Business documents: One of the most popular business
applications you can use to create and edit documents is ”Microsoft Word” with this
word processing application, you can create any type of business document, Microsoft
Word can check spelling errors , correct grammar mistakes, include graphics in the
document. You can also use Microsoft Excel spread sheet to organize data inform of
figures. Spread sheets can help business owners manipulate decision variables and
determine their impacts on outcomes like profits and sales. Using a spread sheet, a
business owner can have an accurate answer to a given question in minutes and can often
glance at the whole financial image of the company on a single page. You can also use
spread sheets to set a price for a proposed product.
7. Transfer of information: Computers can be used to transfer information with in an
organization / business. In this lesson we have already seen that a computer can be used
to store data, so this data can be moved across the company using a computer.
Information can easily move from one level to another using an internal network or
external network. An internal network ensures that information is only shared within the
company, so an infrastructure to move this data is created so that employees and business
managers share data using their computers. Yet for an external network, users will be in
position to access data stored on company database using the internet, in most cases,
companies set up websites which require users to login to access this data.
8. Communication: One of the key factors which drive a business is communication.
Computers can be used to accelerate the communication process within a business. It is
very important to stay in touch with your customers and listen to their needs and
demands, many small businesses are using electronic mail as a communication media to
reach their customers and business partners. Also computers can be used in virtual
communication, in this process both parties need to install a virtual communication
software like SKYPE on their computers and start communication through VIDEO, small
businesses can create group chat rooms on SKYPE for free, this will help them stay in
touch with each other from anywhere.
9. Office and Supply Management: On a daily basis, businesses deal with buying and
selling of goods and services, a computer can be used to manage supplies and inventory
efficiently. Companies like Intacct.com will provide you with a cloud based inventory
management software which will enable you gain control and visibility into inventory

from anywhere using a computer. This all process will help you maximize cost savings
and also improve on capital efficiencies. You can as well use a computer to manage and
track basic supplies in a business, these supplies can include papers, printer-ink, and other
small supplies used on a daily basis in a business.
10. Human Resources Management: Computers can be used to manage, hire and
interview new employees, today, many small businesses and human resource managers
use the internet to find talented individuals. Human resource managers can use a
computer to train new employees on how a business operates and also allocate tasks to
each new employee. Business managers can use computers to monitor the performance of
each individual at work, this process ensures that no employee misuses company
facilities and time.
DISADVANTAGES OF COMPUTERS:
1. Requires Training: In most cases, small business owners don’t know how to use a
computer for business purposes, so they have to hire experts to teach them and their
employees on how to use computers to accomplish specific business tasks. To some
extent, this process is costly and it takes time. For example, if a small business owner
wants to use Quickbooks to manage their accounts , they have to take off time and learn
how Quickbooks works, or they will have to pay an extra fee to hire a Quickbooks expert
to teach them. Even though the end result is good, time and money will be spent during
this process.
2. Computer Crime: Computers are used to provide efficient ways for employees to
share information, but at the same time employees with malicious intentions can use this
opportunity to hack into the system to access private business information for their
personal gains. In most cases this information can be sold to business rivals, which is
harmful to a business. Computer crime is on the rise and many small businesses have
been victims of data loss. Some times employees or outsiders can modify computer
programs to create false information or illegal transactions or install viruses to corrupt
stored information.
3. Require Additional Infrastructure: Integrating computers in a business can be
costly, you don’t stop at buying a computer, you need to invest money in different types
of business software, this software is used to accomplish specific business tasks like
accounting, tracking inventory, sales, data security and so much more. You also have to
invest money in computer maintenance contracts with Geek experts who will service
your computers every month to ensure that they operate efficiently. This all process can
be costly and some small businesses can’t afford them.
4. Replaces Human Labor: If a business decides to use computers to complete most
difficult tasks, humans will not be much needed and this will cause job loss and
unemployment. Lets take a simple example in a Bakery business, electronic temperature

sensors can be used to control and report room temperature in the baking room, in this
case, the bakery will need only one person to monitor results on the computer from the
baking room, if the temperature drops or rises, notifications will be sent to the computer
and the controller will respond immediately. This is a good technology for a business,
because it will guarantee efficiency and quality, but it will also cut off so many people.
5. Unemployment.Different tasks are performed automatically by using computers. It reduces
the need of people and increases unemployment in society.
6. Wastage of time and energy. Many people use computers without positive purpose. They
play games and chat for a long period of time. It causes wastage of time and energy. Young
generation is now spending more time on the social media websites like Facebook, Twitter
etc or texting their friends all night through smartphones which is bad for both studies and
their health. And it also has adverse effects on the social life.
7. Data Security. The data stored on a computer can be accessed by unauthorized persons
through networks. It has created serious problems for the data security.
8. Computer Crimes. People use the computer for negative activities. They hack the credit card
numbers of the people and misuse them or they can steal important data from big
organizations.
9. Privacy violation. The computers are used to store personal data of the people. The privacy
of a person can be violated if the personal and confidential records are not protected properly.
10. Health risks. The improper and prolonged use of computer can results in injuries or disorders
of hands, wrists, elbows, eyes, necks and back. The users can avoid health risks by using the
computer in proper position. They must also take regular breaks while using the computer for
longer period of time. It is recommended to take a couple of minutes break after 30 minutes
of computer usage.
11. Impact on Environment. The computer manufacturing processes and computer waste are
polluting the environment. The wasted parts of computer can release dangerous toxic
materials. Green computer is a method to reduce the electricity consumed and environmental
waste generated when using a computer. It includes recycling and regulating manufacturing
processes. The used computers must be donated or disposed off properly.
USES OF COMPUTERS
USES OF COMPUTER AT HOME
Home Budget
 Computer can be used to manage Home Budget. You can easily calculate your
expenses and income. You can list all expenses in one column and income in
another column. Then you can apply any calculation on these columns to plan
your home budget. There are also specialize software that can manage your
income and expenses and generate some cool reports.
Computer Games
 An important use of computers at home is playing games. Different types of
games are available. These games are a source of entertainment and recreation.

Many games are available that are specially developed to improve your mental
capability and thinking power.
Working from Home
 People can manage the office work at home. The owner of a company can check
the work of the employees from home. He can control his office while sitting at
home.
Entertainment
 People can find entertainment on the internet. They can watch movies, listen to
songs, and watch videos download different stuff. They can also watch live
matches on the internet.
Information
 People can find any type of information on the internet. Educational and
informative websites are available to download books, tutorials etc. to improve
their knowledge and learn new things.
Chatting & Social Media
 People can chat with friends and family on the internet using different software
like Skype etc. One can interact with friends over social media websites like
Facebook, Twitter & Google Plus. They can also share photos and videos with
friends.
USES OF COMPUTERS IN EDUCATION
CBT are different programs that are supplied on CD-ROM. These programs include text,
graphics and sound. Audio and Video lectures are recorded on the CDs. CBT is a low
cost solution for educating people. You can train a large number of people easily.
Benefits of CBT
Some benefits of CBT are as follows:
1. The students can learn new skills at their own pace. They can easily acquire
knowledge in any available time of their own choice.
2. Training time can be reduced.
3. Training materials are interactive and easy to learn. It encourages students to learn
the topic.
4. Planning and timing problems are reduced or eliminated.
5. The skills can be taught at any time and at any place.
6. It is very cost effective way to train a large number of students.
7. Training videos and audios are available at affordable prices.
Computer Aided Learning (CAL)
 Computer aided learning is the process of using information technology to help
teaching and enhance the learning process. The use of computer can reduce the
time that is spent on preparing teaching material. It can also reduce the
administrative load of teaching and research. The use of multimedia projector and
PowerPoint presentations has improved the quality of teaching. It has also helped
the learning process.

Distance Learning
 Distance learning is a new learning methodology. Computer plays the key role in
this kind of learning. Many institutes are providing distance learning programs.
The student does not need to come to the institute. The institute provides the
reading material and the student attends virtual classroom. In virtual classroom,
the teacher delivers lecture at his own workplace. The student can attend the
lecture at home by connecting to a network. The student can also ask questions to
the teacher.
Online Examination
 The trend of online examination is becoming popular. Different examination like
GRE, GMAT and SAT are conducted online all over the world. The questions are
marked by computer. It minimizes the chance of mistakes. It also enables to
announce the result in time.
USES OF COMPUTERS IN BUSINESS
The use of computer technology in business provides many facilities. Businessmen are
using computers to interact with their customers anywhere in the world. Many business
tasks are performed more quickly and efficiently. Computers also help them to reduce the
overall cost of their business. Computer can be used in business in the following ways.
Marketing
 An organization can use computers for marketing their products. Marketing
applications provide information about the products to customers. Computer is
also used to manage distribution system, advertising and selling activities. It can
also be used in deciding pricing strategies. Companies can know more about their
customers and their needs and requirements etc.
Stock Exchange
 Stock Exchange is the most important place for businessmen. Many stock
exchanges use computers to conduct bids. The stockbrokers perform all trading
activities electronically. They connect with the computer where brokers match the
buyers with sellers. It reduces cost as no paper or special building is required to
conduct these activities.

USES OF COMPUTERS IN MEDICAL FIELD
Hospital Management System
 Specialized hospital management softwares are used to automate the day to day
procedures and operations at hospitals. These tasks may be Online appointments,
payroll admittance and discharge records etc.
Patient History
 Hospital management systems can store data about patients. Computers are used
to store data about patients, their diseases & symptoms, the medicines that are
prescribed.
Patients Monitoring
 Monitoring systems are installed in medical wards and Intensive care units to
monitoring patients continuously. These systems can monitor pulse, blood
pressure and body temperature and can alert medical staff about any serious
situations.
Life Support Systems
 Specialized devices are used to help impaired patients like hearing aids.
Diagnosis Purpose
 A variety of softwares are used to investigate symptoms and prescribed
medication accordingly. Sophisticated systems are used for tests like CT Scan,
ECG, and other medical tests.

DUTIES & RESPONSIBILITIES OF COMPUTER PERSONNEL
1. COMPUTER PROGRAMMER
Computer programmers write, test, and maintain the programs that computers follow
when performing specific functions. While job titles and descriptions vary by company,
the main task of computer programmers is problem solving and development of systems
solutions using the appropriate methodologies and techniques.
Programmers often work on projects as a team, each team member assigned according to
strength and ability. A programmer uses programming languages, such as C++, PHP, or
Java to communicate with computer to perform a set of instructions. By typing code in
2nd and 3rd level programming languages (which are languages become more like words
as the generation goes up and more like machine code as the generation goes down , eg
assembler) helps computer programmers easier to code with. Once finished coding they
compile the program into machine language so the computer can follow the set of
instructions.
What types of tasks are involved in Computer Programming?
In addition to writing new programs, computer programmers update and maintain
existing programs. They test programs to ensure efficiency, accuracy, and to identify
programming errors. Some of the tasks programmers might also do the following:
Duties and responsibilities
 Work with field experts to create custom software
 Analyze technical data, designs, and prototypes
 Prepare and present reports on project specifications, activities, and status
 Write computer software, programs, or code
 Document reliability of technical specifications
 Work with software providers to increase proficiencies while working within applications
 Work cross-departmental on development and support
 Prepare software documentation for end users
 Collaborate with business analysts and developers to produce software designs
 Formulate program specifications and basic prototypes
 Transform software designs and specifications into high functioning code in the appropriate
language
 Integrate individual software solutions to higher level systems
 Test code periodically to ensure it produces the desirable results and perform debugging when
necessary
 Perform upgrades to make software and systems more secure and efficient
 Collaborate with technical writers to create documentation for user support

2. SYSTEM ANALYST AND DESIGNERS
Job Titles
 Network Designer
 Systems Analyst
 Solutions Architect
 Senior Systems Engineer
 Senior Solutions Architect
 Systems Architect
 Principal Solutions Architect
Duties and responsibilities
Duties The role of system analysts and designers is critical in contemporary system
development. The systems analyst is a key partner with project managers and system
developers.
Systems analysts define software requirements and specifications and guide program
design and development. A systems analyst may supervise a software development or
maintenance team of analyst / programmers and programmers.
Depending on the level of responsibility and the particular job role involved, duties may
also include:
 Examine and evaluate current systems
 Identify system requirements
 Liaise with users to track additional requirements and features
 Document interfaces between new and legacy systems
 Collaborate with IT team and developers to produce new systems
 Validate changes by testing programs
 Train users on the new operation systems and provide support
 Ensure deadline and budget requirements are met
 Stay up-to-date with current technologies and technical developments
3. DATABASE ADMINISTRATOR
Job Description:
Also called Database Co-ordinator, Database Programmer Closely related jobs Database
Analyst, Database Modeller, Programmer Analyst, Systems Manager
In summary
Database administrators design, implement, maintain and repair an organisation’s
database. The role includes developing and designing the database strategy, monitoring
and improving database performance and capacity, and planning for future expansion
requirements. They may also plan, co-ordinate and implement security measures to
safeguard the database.

A database administrator may
 Building database systems of high availability and quality.
 Designing and implementing databases in accordance to end users information needs and views
 Defining users and enabling data distribution to the right user, in appropriate format and in a timely
manner
 Use high-speed transaction recovery techniques and backup data
 Minimise database downtime and manage parameters to provide fast query responses
 Provide proactive and reactive data management support and training to users
 Determine, enforce and document database policies, procedures and standards
 Perform tests and evaluations regularly to ensure data security, privacy and integrity
 Monitor database performance, implement changes and apply new patches and versions when required
 Undertake daily administration, including monitoring system performance, ensuring successful
backups, and developing/implementing disaster recovery plans
 Manage data to give users the ability to access, relate and report information in different ways
 Develop standards to guide the use and acquisition of software and to protect valuable information
 Modify existing databases or instruct programmers and analysts on the required changes
 Test programs or databases, correct errors and make necessary modifications
 Train users and answer questions
 After the initial design, the DBA must monitor the performance of the database, and if problems
surface (such as a particular report taking an unacceptably long time to produce), appropriate changes
must be made to the database structure.
 Keeping users informed of changes in the database structure that will affect them; for example, if the
size or format of a particular field is altered or additional fields added
 Maintenance of the data dictionary for the database, and responsibility for establishing conventions for
naming tables, columns, indexes & so on.
 Implementing access privileges for all users of the database; that is, specifying which items can be
accessed and / or changed by each user.
 Allocating passwords to each user.
 Providing training to users in how to access and use the database.
 Manage the organization’s,-data resources,-database plans,-design–operations,-training,-user
support,-security & Maintenance
 Maintain data consistency and security
 Approve access to data stored
 Approve access procedures
4. NETWORK ADMINISTRATOR
Job Description:
Closely related jobs: Network Technician, Network Engineer, Website Administrator,
Systems Administrator, Telecommunications Engineer
In summary
Network administrators provide operational support for and management of computer
networks to ensure they run efficiently. The IT networks can range from internet and
private networks to large communications networks.

A network administrator may
 Install, configure and maintain pcs, networking equipment and network operating systems
 Monitor and configure networks to optimize performance and resolve faults
 Undertake recovery action in the event of a system failure
 Establish and control system access and security levels
 Provide training and support for system software
 Implement and co-ordinate housekeeping procedures, including system back-ups, setting up user
accounts, monitoring file access etc.
 Plan and implement maintenance and upgrades for system software and hardware
 Maintain peripheral devices connected to the printer such as printers and scanners
 Fully support, configure, maintain and upgrade corporate customer’s networks and in house servers
 Install and integrate new server hardware and applications
 Keep an eye out for needed updates
 Support and administer third-party applications
 Ensure network security and connectivity
 Monitor network performance (availability, utilization, throughput, good put, and latency) and test for
weaknesses
 Set up user accounts, permissions and passwords
 Resolve problems reported by end user
5. SYSTEMS ADMINISTRATOR
 Install and configure software and hardware
 Manage network servers and technology tools
 Set up accounts and workstations
 Monitor performance and maintain systems according to requirements
 Troubleshoot issues and outages
 Ensure security through access controls, backups and firewalls
 Upgrade systems with new releases and models
 Develop expertise to train staff on new technologies
 Build an internal wiki with technical documentation, manuals and IT policies
6. COMPUTER SECURITY SPECIALISTS
 Plan, coordinate, and implement the organization’s information security.
 Educate users about computer security,
 Install security software,
 Monitor the network for security breaches,
 Respond to cyber-attacks, and, in some cases,
 Gather data and evidence to be used in prosecuting cyber-crime.
 Designing and implementing safety measures and controls
 Monitoring network activity to identify vulnerable points
 Acting on privacy breaches and malware threats
 Analyze IT specifications to assess security risks
 Design and implement safety measures and data recovery plans
 Install, configure and upgrade security software (e.g. antivirus programs)
 Secure networks through firewalls, password protection and other systems
 Inspect hardware for vulnerable points of access
 Monitor network activity to identify issues early and communicate them to IT teams

 Act on privacy breaches and malware threats
 Serve as a security expert and conduct trainings when needed
 Draft policies and guidelines
7. COMPUTER SCIENTISTS
 Work as theorists, researchers, or inventors.
 Their jobs are distinguished by the higher level of theoretical expertise and innovation they apply
to complex problems and the creation or application of new technology.
 Those employed by academic institutions work in areas ranging from complexity theory to
hardware to programming-language design.
 Some work on multidisciplinary projects, such as developing and advancing uses of virtual reality,
extending human-computer interaction, or designing robots.
 Their counterparts in private industry work in areas such as applying theory; developing
specialized languages or information technologies; or designing programming tools, knowledge-
based systems, or even computer games.
8. DATA ENTRY CLERK
 Transfer data from paper formats into computer files or database systems using
keyboards, data recorders or optical scanners
 Type in data provided directly from customers
 Create spreadsheets with large numbers of figures without mistakes
 Verify data by comparing it to source documents
 Update existing data
 Retrieve data from the database or electronic files as requested
 Perform regular backups to ensure data preservation
 Sort and organize paperwork after entering data to ensure it is not lost
Research – important area
1. FIND OUT THE DUTIES AND RESPONSIBILITIES OF THE FOLLOWING
a) Computer programmer
b) System analyst
c) System administrator
d) Computer librarian
e) Data preparation staff
f) Network administrator
g) Data control staff
h) IT manager
i) Data processing manager
j) Computer operators
k) Data capturing clerk
2. Write notes on
DATA PROCESSING METHODS
a) Manual data processing
b) Mechanical data processing
c) Electronic data processing
d) Automatic data processing
e) Online data processing
f) Distributed data processing
g) Centralized data processing
h) Transaction processing
i) Decentralized data processing
j) Time sharing data processing
k) Batch or offline data processing

COMPUTER PERFORMANCE
Computer performance is characterized by the amount of useful work accomplished by
a computer system or computer network compared to the time and resources used.
Depending on the context, high computer performance may involve one or more of the
following:
 Short response time for a given piece of work
 High throughput (rate of processing work)
 Low utilization of computing resource(s)
 High availability of the computing system or application
 Fast (or highly compact) data compression and decompression
 High bandwidth
 Short data transmission time
What affects a computers performance?
1. The speed of the CPU
2. The size of the ram (random access memory)
3. The speed of the hard disk
4. Hard disk space
5. Multiple applications running on the computer
6. Type of graphic card
7. Defragmenting files
8. Data bus type and size.
9. Clock rate.
10. Cache presence and size.
11. CD-ROM drives speed.
12. MMX processors.
1) THE SPEED OF THE CPU
The speed of the CPU is also known as the clock speed of the CPU. The clock speed of
the CPU is the frequency of which the processor executes instructions or the frequency
by which data is processed by the CPU. It is measured in millions of cycles per second or
megahertz (MHz). If the Clock speed of the CPU is fast then definitely the performance
of the computer will be affected positively, in other words the computer will carry out
processing functions at a faster pace.
 The CPU
High performance, compatibility and upgradability are features that are important. The
higher the generation, the better. For example, because of high performance new features,
Pentium 75 (fifth generation with the clock rate 75 MHz) will outperform 80486DX100
(which is the fourth generation CPU with the clock rate 100MHz).
Another important feature is word size measured in bits. 80386 and 80486 processors are

32 bit whereas Pentiums are 64 bit processors, thus Pentiums can transfer twice as much
data at a time compared to third and fourth generation CPUs.
2) THE SIZE OF THE RAM (RANDOM ACCESS MEMORY)

The RAM is referred to as the active part of the computer. This is because the RAM has
the capability of storing data that the computer is currently using, because of the fact that
it is fast to retrieve data stored in the RAM. With the definition above, a large RAM size
will mean a faster computer performance and a smaller RAM size will result to slower
computer performance.
RAM.
It does not make much sense to have a fast processor if you dont have fast RAM. But
note: faster RAM is more expensive.
The amount of RAM is also important. Today, advanced operating systems require at
least 4 megabytes of memory just to boot up a computer. Using more than one
application at a time requires at least 8 megabytes, and reasonable performance today
calls for 16 megabytes or more. The benefits of adding more RAM include letting you
open more applications at the same time, and working with large files or documents.
More memory may also make your machine run much faster.
The quality of DRAM chips used in a memory module is the most important component
in determining the overall quality and reliability of RAM. So which chips to consider?
Enhanced Data Output (EDO) DRAM provides faster data throughput. Systems using
EDO DRAM will be faster than similar systems using regular DRAM. EDO DRAM
provides even higher performance benefit when used with an L2 cache.
Enhanced DRAM (EDRAM) can be thought of as RAM that carries its own cache on
each module. In an EDRAM-based system, essentially the entire system memory bank is
the cache. This can provide dramatic performance improvements. However, at this time,
EDRAM is scarce, very expensive and has not been adopted by many system vendors.
3) THE SPEED OF THE HARD DISK

The hard disk speed is defined as the rate at which material and content can be read and
written on it. The hard disk speed of different hard disks is not consistent because they
vary by manufacturer, drive type and the use of the hard disk. It therefore means that the
higher the speed of the hard disk the faster the performance of the computer and vice
versa.
4) HARD DISK SPACE

The bigger the space on the hard disk will result to faster performance of the computer.
The smaller the space on the hard disk will result in a slower performance of the
computer. The hard disk is filled with data this will use most of the memory leaving less
memory for the operations of the processor.

 Hard disk capacity and seek time.
High-performance hard drives have at least 1.2 G of capacity, provide an average seek
time of 12 milliseconds, a 128 to 256 K hard disk buffer cache with both write-caching
and read-caching capabilities, and spin about 4,500 rotations per minute. (You may be
familiar with using a disk cache, such as Microsoft SmartDrive, which uses a small RAM
buffer to speed up access to a large hard disk.)
5) MULTIPLE APPLICATIONS RUNNING ON THE COMPUTER

Multi-tasking tends to slow down the performance of the computer because memory is
used to support more than one applications compared to when one application has all the
memory to itself. This means that the more applications that are running the slower the
computer will perform. Likewise if less or one application is running the performance of
the computer will be faster.
6) TYPE OF GRAPHIC CARD

When it comes to quality of pictures and animations graphic cards are the main factors.
So if a machine processes many graphics and it has a weak graphic card it will perform
slower. This means that the more powerful the graphic card is the faster the performance
of the computer.
Video card
A full-featured PCI-compliant VGA card, with at least 1 to 2 GB of video RAM, will
further accelerate graphics performance.
7) DEFRAGMENTING FILES

Files that are broken or it takes long to read them will mean that the computer will have
to defragment them first. This will slow down the performance of the computer.
8). DATA BUS TYPE AND SIZE.

The data bus is the highway that carries information between the processor and the
memory subsystem. The wider the data bus, the more information it can transfer. Because
of its external 64-bit data bus, the Pentium processor can transfer data to and from
memory at rates up to 528 Mbytes/second (five times faster than the transfer rate of the
Intel486 (TM) DX2-66MHz microprocessor).
The PCI local bus greatly improves I/O performance. It can transfer data between the
processor and the peripherals at up to 132 MB/second, far faster than the ISA bus rate of
5 MB/second
9). CLOCK RATE.

Since any step of processing can happen only on the "tick" of the clock (called clock
cycle), the faster the rate the quicker the CPU works. The Intel486(TM) processor, for
example, is able to execute many of its instructions in one clock cycle, while previous
generations of Intel microprocessors require multiple clock cycles to execute a single
instruction. The Pentium processors have the ability to execute multiple instructions per

clock cycle due to the fact that the Pentium processor's two pipelines can execute two
instructions simultaneously. If other modules of the system require more than one clock
pulse, the CPU has to wait for them to keep up. This is called a wait state.
10. CACHE PRESENCE AND SIZE.

L1 Cache.
The bigger the on-chip cache size, the better since more instructions and data can be
stored on the chip, reducing the number of times the processor has to access slower, off-
chip memory areas to get data. For example, Intel has doubled on-chip cache size to 32K
on the Intel Pentium processor with MMX technology.
L2 Cache.
System memories composed of dynamic RAM (DRAM) alone have not been able to keep
up with the dramatic increases in CPU speeds over the years. In order to optimize the
memory performance in these systems, designers are implementing architectures using
cache memory, resulting in speed increases up to 45%. Expanding secondary cache (e.g.
from 128K to 512K) can greatly improve the performance of some applications.
In a recent industry magazine test of notebook computers, a 486 machine with L2 cache
outperformed a Pentium 90 machine without L2 cache by 30%.
11. CD-ROM drives speed.

At the time of writing of these notes the slowest CD-ROM drive available on the market
is quad speed. It may be enough, if you are not running applications from CD-ROM, but
only installing them. Otherwise look at octal or ten-speed technologies.
12. MMX processors.

Multimedia extensions processors (MMX) is designed specifically to support media-rich
software and communications applications.. The Pentium processor with MMX
technology will give a better, smoother and more realistic multimedia experience. These
processors have got 57 powerful new instructions specifically designed to manipulate and
process video, audio and graphical data efficiently. However, your system will require
software designed for MMX technology (old software must be recompiled to take
advantage of new MMX features).

HARDWARE SUMMARY
Hardware represents the physical and tangible components of a computer i.e. the
components that can be seen and touched.
Examples of Hardware are following:
 Input devices -- keyboard, mouse etc.
 Output devices -- printer, monitor etc.
 Secondary storage devices -- Hard disk, CD, DVD etc.
 Internal components -- CPU, motherboard, RAM etc.
Relationship between Hardware and Software
Hardware - Physical components that make up a computer system.
Software - Computer programs and related data that provide the instructions for telling
computer hardware what to do and how to do it.
 Hardware and software are mutually dependent. Both of them must work together
to make a computer produce a useful output.
 Software cannot be utilized without supporting hardware.
 Hardware without set of programs to operate upon cannot be utilized and is
useless.
 To get a particular job done on the computer, relevant software should be loaded
into the hardware.
 Software acts as an interface between the user and the hardware.
 Hardware is the body and software is the soul.
 Hardware does all the work as like our body. But it’s the software which instructs
(Set of instructions are passed to the processor for each process to be done) the
hardware what to do.
For example when you switch on the computer it is the BIOS which first checks
the hardware and booting order and then instructs the hardware to load(boot) the
OS from the hard-disc or pen-drive or external drive or the cd/dvd drive. once the
instruction is passed the hardware starts to function according to the instruction
received.

SOFTWARE
The intangible computer components, which are the programs or instructions of the computer.
Everything that a computer does, it acts under instructions written out as computer programs. The
hardware needs these instructions to function.
Computer software refers to the various programs or instructions that are stored in the
computer (stored program concept) and used to either manage or control the operation of
a computer system or to direct the computer in solving specific problems. Software is
divided into two major types.
SOFTWARE HIERARCHY
System Software Application Software
 System software controls how the
computer system works and it enables
the user to access the system hardware
and application software.
 Applications software does not control the
system; instead it allows the user to perform
everyday tasks such as creating a document
or webpage.
 Close to system  Close to user
 Difficult to design  Easy to design
 Less interactive  More interactive
 Fast in speed  Slow in speed
 Generally written in low-level language  Generally written in high-level language
 Smaller in size  Bigger in size and requires large storage
space
 Difficult to manipulate  Easy to manipulate and use
 Difficult to understand  Easy to understand

1. SYSTEM SOFTWARE
The system software is collection of programs designed to operate, control, and extend
the processing capabilities of the computer itself. System software are generally prepared
by computer manufactures. These software products comprise of programs written in
low-level languages which interact with the hardware at a very basic level. System
software serves as the interface between hardware and the end users.
Some examples of system software are Operating System, Compilers, Interpreter,
Assemblers etc.
System software is computer software designed to operate the computer hardware and to
provide a platform for running application software.
The most basic types of system software are:
 The computer BIOS and device firmware, which provide basic functionality to
operate and control the hardware connected to or built into the computer.
 The operating system (prominent examples being Microsoft Windows, Mac OS X
and Linux), which allows the parts of a computer to work together by performing
tasks like transferring data between memory and disks or rendering output onto a
display device. It also provides a platform to run high-level system software and
application software.
 Utility software, which helps to analyze, configure, optimize and maintain the
computer.
In some publications, the term system software is also used to designate software
development tools (like a compiler, linker or debugger).
Types of system software programs
System software helps use the operating system and computer system. It includes
diagnostic tools, compilers, servers, windowing systems, utilities, language translator,
data communication programs, database systems and more. The purpose of system
software is to insulate the applications programmer as much as possible from the
complexity and specific details of the particular computer being used, especially memory
and other hardware features, and such accessory devices as communications, printers,
readers, displays, keyboards, etc.
Specific kinds of system software include:
 Loaders
 Linkers
 Utility software

 Desktop environment / Graphical user interface
 Shells
 BIOS
 Hypervisors
 Boot loaders
 Database Management Systems(SQL, NoSQL)
If system software is stored on non-volatile memory such as integrated circuits, it is
usually termed firmware.
3 functional categories of system software
System management programs
 Programs that manage the hardware, software, and data resources
of the computer system during its execution of the various
information processing jobs of users.
 The most important system management programs are operating
systems and operating environments, followed by
telecommunications monitors & Database Management Systems.
System support programs
 Programs that support the operations and management of a
computer system by providing a variety of support services.
 Major support programs are system utilities, performance
monitors, & security monitors.
System development programs
 Programs that help users develop information system
programs and procedures and prepare user programs for
computer processing.
Major development programs are language translators, programming tools and CASE
[computer-aided software engineering] packages
Features of system software are as follows:
 Close to system
 Fast in speed
 Difficult to design
 Difficult to understand
 Less interactive
 Smaller in size
 Difficult to manipulate
 Generally written in low-level language

1. APPLICATION SOFTWARE
o Applications software comprises programs designed for an end user, such as word
processors, database systems, and spreadsheet programs.
o Programs that specify the information processing activities required for the
completion of specific tasks of computer users. E.g. Electronic Spreadsheet and
word processing programs or inventory or payroll programs.
 Software that is designed and written for a specific personal, organizational, or
processing task, such as graphics software.
 These programs accomplish the specialized tasks of the user, while operating
system software allows the computer to work. A computer-aided dispatch system
is application software, as is each word processing program.
Features of application software are as follows:
 Close to user
 Easy to design
 More interactive
 Slow in speed
 Generally written in high-level language
 Easy to understand
 Easy to manipulate and use
 Bigger in size and requires large storage space
FREEWARE
 Public domain software that is freely available in magazines and on the
internet at no charge to users though manuals may be offered at a cost.
Freeware may or may not have copyrights and may or may not have
distribution restrictions.
SHAREWARE
 Refers to software that is widely distributed in much the same way as
freeware BUT is always copyrighted and includes a software license that
requires its users to pay for the privilege of using the software beyond a
certain trial period. If you decide to use it, you are expected to pay for the
license. There is usually a disabling system in the program after a certain
period of time i.e. a month.

OPERATING SYSTEM
It is a program with following features:
 An operating system is a program that acts as an interface between the software
and the computer hardware.
 It is an integrated set of specialized programs that are used to manage overall
resources and operations of the computer.
 It is specialized software that controls and monitors the execution of all other
programs that reside in the computer, including application programs and other
system software.
Examples include
 AmigaOS
 Android
 HP-UX
 iOS
 IRIX
 Linux
 MAC OS 8
 MAC OS 9
 MAC OS 10
 MAC OS X
 MS-DOS
 Unix
 Vector Linux
 Windows 2000
 Windows 2003
 Windows 3.X
 Windows 7
 Windows 8
 Windows 95
 Windows 98
 Windows 10
 Windows CE
 Windows ME
 Windows NT
 Windows Vista
 Windows XP
 Xenix
 Windows 10

TYPES OF OPERATING SYSTEMS / OPERATING SYSTEM TYPES
As computers have progressed and developed, so have the operating systems. Below is a
basic list of the types of operating systems and a few examples of operating systems that
fall into each of the types. Many computer operating systems will fall into more than one
of the below types.
1. GUI
Short for Graphical User Interface, a GUI operating system contains graphics and icons
and is commonly navigated by using a computer mouse. Examples of GUI operating
systems are:
 System 7.x
Windows 98
Windows CE
2. MULTI-USER
A multi-user operating system allows for multiple users to use the same computer at the
same time and different times. Examples of operating systems that would fall into this
category are:
 Linux
Unix
Windows 2000
A multi-user operating system extends the basic concept of multi-tasking with
facilities that identify processes and resources, such as disk space, belonging to
multiple users, and the system permits multiple users to interact with the system at the
same time.
3. MULTIPROCESSING
An operating system capable of supporting and utilizing more than one computer
processor. Examples of operating systems that would fall into this category are:
 Linux
Unix
Windows XP
4. MULTITASKING
An operating system that is capable of allowing multiple software processes to run at the
same time. Examples of operating systems that would fall into this category are:
 Linux
Unix
Windows 8
It is characterized in preemptive and co-operative types. In preemptive multitasking,
the operating system slices the CPU time and dedicates a slot to each of the programs.
Unix-like operating systems, e.g., Solaris, Linux, as well as AmigaOS support

preemptive multitasking. Cooperative multitasking is achieved by relying on each
process to provide time to the other processes in a defined manner. 16-bit versions of
Microsoft Windows used cooperative multi-tasking. 32-bit versions of both Windows
NT and Win9x, used preemptive multi-tasking.
5. MULTITHREADING
Operating systems that allow different parts of a software program to run concurrently.
Examples of operating systems that would fall into this category are:
 Linux
Unix
Windows XP
6. Single-task
A single-tasking system can only run one program at a time, while a multi-tasking
operating system allows more than one program to be running in concurrency. This is
achieved by time-sharing, dividing the available processor time between multiple
processes that are each interrupted repeatedly in time slices by a task-scheduling
subsystem of the operating system.
7. Single-user
Single-user operating systems have no facilities to distinguish users, but may allow
multiple programs to run in tandem.
8. Time-sharing
Time-sharing operating systems schedule tasks for efficient use of the system and
may also include accounting software for cost allocation of processor time, mass
storage, printing, and other resources to multiple users.
9. Distributed
A distributed operating system manages a group of distinct computers and makes
them appear to be a single computer. The development of networked computers that
could be linked and communicate with each other gave rise to distributed computing.
Distributed computations are carried out on more than one machine. When computers
in a group work in cooperation, they form a distributed system.
10.Templated
In an OS, distributed and cloud computing context, templating refers to creating a
single virtual machine image as a guest operating system, then saving it as a tool for

multiple running virtual machines. The technique is used both in virtualization and
cloud computing management, and is common in large server warehouses.
11.Embedded
Embedded operating systems are designed to be used in embedded computer systems.
They are designed to operate on small machines like PDAs with less autonomy. They
are able to operate with a limited number of resources. They are very compact and
extremely efficient by design. Windows CE and Minix 3 are some examples of
embedded operating systems.
12.Real-time
A real-time operating system is an operating system that guarantees to process events
or data by a specific moment in time. A real-time operating system may be single- or
multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that
a deterministic nature of behavior is achieved. An event-driven system switches
between tasks based on their priorities or external events while time-sharing operating
systems switch tasks based on clock interrupts
13.Library
A library operating system is one in which the services that a typical operating system
provides, such as networking, are provided in the form of libraries. These libraries are
composed with the application and configuration code to construct unikernels –
which are specialized, single address space, machine images that can be deployed to
cloud or embedded environments.
MODES OF OPERATION/ OPERATING SYSTEM TECHNIQUES
CLASSIFICATION OF OPERATING SYSTEMS
1. Multi-user: Allows two or more users to run programs at the same time. Some
operating systems permit hundreds or even thousands of concurrent users.
2. Multiprocessing : Supports running a program on more than one CPU.
3. Multitasking : Allows more than one program to run concurrently.
4. Multithreading : Allows different parts of a single program to run concurrently.
5. Real time: Responds to input instantly. General-purpose operating systems, such as
DOS and UNIX, are not real-time.
Computers can operate in many different ways requiring different and complex
operating systems.

Real time processing
 When the computer has to react within a guaranteed time to an input, a real
time operating system is used. For example, the engine management system
within a car uses a real time operating system in order to react to all the things
going on within the engine. A real time operating system does not necessarily
have to be fast. It simply has to be quick enough to respond to inputs in a
predictable way. Embedded computers often contain an RTOS as many are
used to control something.
 Computers operating in real time are often dedicated to the control of systems
such as industrial processes, planes and space flights. Another example of real
time processing is computer games. For example, when an action is selected
in a game, the data is fed back to the computer and the systems updated.
Multi-programming
 Multi-programming is a method of operating such that several programs
appear to be running at once.
 The jobs are usually given priorities. The operating system switches jobs in
and out of processor time according to priority. For example, while one job is
being allocated printer time, another will be being processed in memory. The
processor is so fast that it seems that many jobs are being processed at the
same time.
Multi-tasking
 This isn't just about running more than one application at the same time.
Multi-tasking allows multiple tasks to run concurrently, taking turns using
the resources of the computer.
 This can mean running a couple of applications, sending a document to the
printer and downloading a web page.
 However, operating systems are not truly multi-tasking - in order to do this,
you would need parallel processors, which are now appearing on personal
computers.
Multiprocessing
 An operating system technique which can manage multiple instruction processors,
assigning each to operate upon a different instruction stream (program or job)
concurrently.
 Multiprocessing is the use of two or more central processing units (CPUs) within
a single computer system. The term also refers to the ability of a system to
support more than one processor and/or the ability to allocate tasks between
them.There are many variations on this basic theme, and the definition of
multiprocessing can vary with context, mostly as a function of how CPUs are
defined (multiple cores on one die, multiple chips in one package, multiple
packages in one system unit, etc.).
 Multiprocessing sometimes refers to the execution of multiple concurrent
software processes in a system as opposed to a single process at any one instant.
However, the terms multitasking or multiprogramming are more appropriate to
describe this concept, which is implemented mostly in software, whereas
multiprocessing is more appropriate to describe the use of multiple hardware

CPUs. A system can be both multiprocessing and multiprogramming, only one of
the two, or neither of the two.
Multi-access or multi-user
 A multi-access (or multi-user) system is one where a number of users are able to
use the same system together.
 Modern personal computers can allow multi user access i.e. more than one person
can make use of the computer resources at the same time via a LAN.
 The central processor deals with users in turn; clearly the more users, the slower
the response time. Generally, however, the processor is so fast that the response
time at the most is a fraction of a second and the user feels they are being dealt
with immediately.
o Multi-user is a term that defines an operating system or application
software that allows concurrent access by multiple users of a computer.
Time-sharing systems are multi-user systems. Most batch processing
systems for mainframe computers may also be considered "multi-user", to
avoid leaving the CPU idle while it waits for I/O operations to complete.
However, the term "multitasking" is more common in this context.
o An example is a UNIX server where multiple remote users have access
(such as via Secure Shell) to the UNIX shell prompt at the same time.
Another example uses multiple X Window sessions spread across multiple
terminals powered by a single machine - this is an example of the use of
thin client.
o Management systems are implicitly designed to be used by multiple users,
typically one system administrator or more and an end-user community.
Single-user
 Is most commonly used when talking about an operating system being usable only
by one person at a time, or in reference to a single-user software license
agreement.E.g. MSDOS.
Batch processing
 A batch processing system is where programs or data are collected together in a
batch and processed in one go. Typically the processing of payrolls, electricity
bills, invoices and daily transactions are dealt with this way.
 This method of operation lends itself to jobs with similar inputs, processing and
outputs where no human intervention is needed. Jobs are stored in a queue until
the computer is ready to deal with them. Often batch processed jobs are done
overnight.
OBJECTIVES OF OPERATING SYSTEM
 To make a computer system convenient to use in an efficient manner
 To hide the details of the hardware resources from the users
 To provide users a convenient interface to use the computer system
 To act as an intermediary between the hardware and its users and making it easier
for the users to access and use other resources
 To manage the resources of a computer system

 To keep track of who is using which resource, granting resource requests,
according for resource using and mediating conflicting requests from different
programs and users
 To provide efficient and fair sharing of resources among users and programs
CHARACTERISTICS OF OPERATING SYSTEM
 Memory Management -- keeps tracks of primary memory i.e. what part of it is in
use by whom, what part is not in use etc. and allocates the memory when a
process or program requests it.
 Processor Management -- allocates the processor (CPU) to a process and
deallocates processor when it is no longer required.
 Device Management -- keeps track of all devices. This is also called I/O
controller that decides which process gets the device, when, and for how much
time.
 File Management -- allocates and de-allocates the resources and decides who
gets the resources.
 Security -- prevents unauthorized access to programs and data by means of
passwords and similar other techniques.
 Job accounting -- keeps track of time and resources used by various jobs and/or
users.
 Control over system performance -- records delays between request for a
service and from the system.
 Interaction with the operators -- The interaction may take place via the console
of the computer in the form of instructions. Operating System acknowledges the

same, does the corresponding action and informs the operation by a display
screen.
 Error-detecting aids -- Production of dumps, traces, error messages and other
debugging and error-detecting methods.
 Coordination between other software and users -- Coordination and
assignment of compilers, interpreters, assemblers and other software to the
various users of the computer systems.
MAJOR OPERATING SYSTEMS
MS-DOS (Microsoft Disk Operating System)
 It has been widely used especially before 1995 when the new Windows 95 took over.
 It is a single user operating system – only one user can be using the system at a given
time.
 It is a single tasking operating system – It allows for the processing of only one task at a
time
 Use of short prompt commands – the user interfaces with the computer system through
the use of commands that are fed into the computer usually after the prompt sign (>) e.g.
C:>cls (Command to clear the screen)
 Instructions are put in only through the keyboard
 Once a file is deleted it can never be recalled
 The operating system is not user-friendly
Windows
 Windows based operating system is more advanced than the MS-DOS based operating
system.
 It features graphical user interfaces (GUIs) – User can feed commands into the computer
through the selection of relevant icons, bars, buttons, boxes or other forms of images
(mostly resembling the intended device or operation).
 True multitasking – the operating system allows for numerous tasks to be done at the
same time.
 Networking – the operating system is multi-usable – many users can use it at the same
time. It is capable of holding a number of computer systems networked together.
 Multimedia Presentations- the operating system allows for the presentation of
information in a variety of media including text, graphic displays, voice and other audio,
photographs and video.
 Virtual Memory – It allows for the use of storage devices as extension of the main
memory thus giving the appearance of a larger main memory than actually exists.
 Deleted files go to the recycle bin
 Makes use of easier input methods, e.g. mouse, joystick
 Windows operating system has MS-DOS option
 Examples of Windows Operating Systems packages, Windows NT (new technology) and
Windows 95.
 In computer terms, a window is one section of a computer’s multiple section display
screen that can have a different display.

OS/2
 It is called the Operating System /2
 It is an operating system developed by IBM and was introduced in 1994 with the
OS/2 Warp version as the latest one.
 It provides graphical user interfaces (GUIs), multitasking, virtual memory and
telecommunications.
UNIX
 Originally developed by AT&T but now being offered by many other vendors.
 It is a multitasking, multi-user and net-work managing operating system
 Because of its portability, it can be used on mainframes, midrange computers and
microcomputers.
 It is a popular choice for network servers.
The Macintosh System/Mac OS
 It is an operating system for Apple from Macintosh microcomputers
 It is a popular GUI as well as multitasking and virtual memory operating system.
Types /EXAMPLES of operating systems
There are several types of operating system, defined according to whether they can
simultaneously manage information measuring 16 bits, 32 bits, 64 bits or more.
OPERATING SYSTEM PROGRAMMING SINGLE USER MULTI USER SINGLE TASK MULTI TASK
1. MS DOS 16 bits X X
2. Windows3.1 16/32 bits X not pre-emptive
3.Windows95/98/Me 32 bits X cooperative
4.WindowsNT/2000 32 bits X pre-emptive
5.WindowsXP 32/64 bits X pre-emptive
6.Unix / Linux 32/64 bits X pre-emptive
7.MAC/OS X 32 bits X pre-emptive
8.VMS 32 bits X pre-emptive
9.Windows Vista 32/64 bits X pre-emptive
10.Windows 7, 8, 10 32/64 bits X pre-emptive
BOOTING (also known as "booting up") is a bootstrapping process that starts operating
systems when the user turns on a computer system. A boot sequence is the initial set of
operations that the computer performs when power is switched on. The bootloader
typically loads the main operating system for the computer.

FACTORS ONE SHOULD CONSIDER WHEN
 Making comparisons of the microcomputer operating systems
available in the organization
 Making microcomputer operating system acquisition decision.
 Is the OS a single or multitasking operating system? Many microcomputer
OS are single tasking, meaning they allow only one person to run one program
at a time. Multitasking and multi-user OS permit more than one program to
run and more than one person to use the system at one time. Multitasking OS
may allow a user to receive a fax message at the same time one is searching a
database.
 Is it a task switching operating system? A task switching OS lets one load
more than one program at a time and allows switching between the programs.
The task that one is working with is the foreground task and the suspended
tasks are background tasks.
 What utilities are available with the OS? Some of the most commonly used
utilities on microcomputer OS are delete, copy contents of one diskette to
another, format a diskette, delete files stored in a diskette, and compress data.
 Is the OS hardware dependent? An OS may be limited to running on
specific hardware or may have versions that allow it to run on different types
of computer systems.
 What user interface is offered by the operating system? Graphical User
Interface and Command Driven User Interface are examples of user
interfaces. See Interface section.
ROLES (functions) OF THE OPERATING SYSTEM– see characteristics above
The operating system has various roles:
1. MANAGEMENT OF THE PROCESSOR:
The operating system is responsible for managing allocation of the processor between
the different programs using a scheduling algorithm. The type of scheduler is totally
dependent on the operating system, according to the desired objective.
The OS is responsible for managing the allocation of processor time to the different
programs that will be using the computer. The processor can only execute one
instruction at a time and in a multi-user system, conflicts are bound to arise when
several user programs request usage of the processor at the same time. The OS
therefore allocates processor time to all users either in a round robin fashion or using
a system of priorities.
2. MANAGEMENT OF THE RANDOM ACCESS MEMORY:
The operating system is responsible for managing the memory space allocated to
each application and, where relevant, to each user. If there is insufficient physical
memory, the operating system can create a memory zone on the hard drive, known as

"virtual memory". The virtual memory lets you run applications requiring more
memory than there is available RAM on the system. However, this memory is a great
deal slower.
The OS is responsible for managing the memory space allocated to each application.
If there is insufficient physical memory the OS can create a memory zone on the hard
drive known as virtual memory which lets you run applications requiring more
memory than is available on the system.
The operating system is responsible for the following activities in connections with
memory management.
Keep track of which parts of memory are currently being used and by whom.
Decide which processes to load when memory space becomes available.
Allocate and deallocate memory space as needed
3. MANAGEMENT OF INPUT/OUTPUT:
The operating system allows unification and control of access of programmes to
material resources via drivers (also known as peripheral administrators or
input/output administrators).
4. MANAGEMENT OF EXECUTION OF APPLICATIONS:
The operating system is responsible for smooth execution of applications by
allocating the resources required for them to operate. This means an application that
is not responding correctly can be "killed".
5. MANAGEMENT OF AUTHORISATIONS:
The operating system is responsible for security relating to execution of programmes
by guaranteeing that the resources are used only by programs and users with the
relevantauthorizations.
6. FILE MANAGEMENT:
The operating system manages reading and writing in the file system and the user and
application file access authorizations.
The OS manages reading from and writing to files and also controls the creation,
manipulation and access to files.
The operating system is responsible for the following activities in connections with
file management:
 File creation and deletion
 Directory creation and deletion
 Support of primitives for manipulating files and directories
 Mapping files onto secondary storage
 File backup on stable (nonvolatile) storage media
7. INFORMATION MANAGEMENT:
The operating system provides a certain number of indicators that can be used to
diagnose the correct operation of the machine.
8. ERROR DETECTION

The OS is responsible for detecting and any hardware or software malfunctioning and
reporting them to the user
9. USER/SYSTEM INTERFACE
The OS acts as an interface between the computer and the user, hiding all the
complexities of the computer from the user and making the computer more user
friendly
10. PREPARATION OF A SYSTEM LOG
The OS compiles a report on the events that take place in a computer from the time a
user logs on to a computer, what he/she does up to the time he/she logs off
Additional Functions of the operating system:
 Controls and coordinates the computer system
 Scheduling and loading of jobs to provide continuous processing. So that no
parts of the computer system are idle for any significant period of time.
 It is a platform for application programs
 Provides user interface
 Acts as an interface between hardware and application programs
 Provides error correctional routines
 Control over selection and operation of input-output devices & file handling.
 Records details of processing for control analysis
 File management, control the creation, deletion, saving and access of files
 Memory management, allocates memory to various jobs or tasks
 Multiprogramming, multiprocessing, multitasking, timesharing, housekeeping &
handling errors.
 Resource management manages processor time, memory space, disk space and
peripheral devices.
 Reports errors when they occur.
 Task management. Manage the accomplishment of the computing tasks of end
users. It may involve multitasking capability where several computing tasks can
occur at the same time.
 Minimizes the amount of human intervention required during processing.
COMPUTER INTERFACE
 Is part of the operating system that allows you to communicate with it or the
computer so that you can load programs, access files, and accomplish other tasks?
 When a person interacts with a computer he uses a User Interface, which can be a
screen, keyboard, mouse, scanners or other input devices.
 The interaction between the computer and the user or the control of the flow of
data between a computer and its peripherals.
 Basically the interface can be

 Command driven- include operating systems and database languages
that provide users with flashes of text and in which users would
generally type in their command to perform an action.
 Menu driven
 GUI- point and click
 WIMP interface
1. Command line interfaces (MS-DOS BASED OPERATING SYSTEM)
 A command line interface allows the user to interact with the computer by typing
in commands. The computer displays a prompt, the user keys in the command
and presses enter or return.
 A COMMAND-LINE INTERFACE (CLI) is a mechanism for interacting with
a computer operating system or software by typing commands to perform specific
tasks. This text-only interface contrasts with the use of a mouse pointer with a
graphical user interface (GUI) to click on options, or menus on a text user
interface (TUI) to select options.
Features of a command line interface include:
In the early days of personal computers, all PCs used command-line interfaces.
 Commands - usually abbreviated - must be typed correctly and in the right order
or the command will not work.
 Experienced users who know the commands can work very quickly without
having to find their way around menus.
 An advantage of command driven programs is that they do not need the memory
and processing power of the latest computer and will often run on lower spec
machines.
 Command driven programs do not need to run in Windows.
 A command line interface can run many programs, for example a batch file could
launch half a dozen programs to do its task.
 An inexperienced user can sometimes find a command driven program difficult
to use because of the number of commands that have to be learnt.
An example of a common command-driven interface is MS-DOS, the original operating
system for all Microsoft-compatible PCs. The MS-DOS command to display all files on
drive a would be: dir c:.

2. Graphical user interfaces (WINDOWS BASED OPERATING SYSTEM)
 Graphical user interface is sometimes shortened to GUI.
 The user chooses an option usually by pointing a mouse at an icon representing
that option. A GRAPHICAL USER INTERFACE (GUI) is a type of user
interface item that allows people to interact with programs in more ways than
typing such as computers; hand-held devices such as MP3 Players, Portable
Media Players or Gaming devices; household appliances and office equipment
with images rather than text commands. A GUI offers graphical icons, and visual
indicators, as opposed to text-based interfaces, typed command labels or text
navigation to fully represent the information and actions available to a user.
Features of GUIs include:
 They are much easier to use for beginners.
 They enable you to easily exchange information between software using cut and
paste or 'drag and drop'.
 They use alot of memory and processing power. It can be slower to use than a
CLI if you are an expert user.
 They can be irritating to experienced users when simple tasks require a number of
operations.
When discussing user interfaces, it is important to note that Windows XP, OS/X and
Linux are all graphical user interfaces.
A good user interface should:
 Be attractive and pleasing to the eye
 Allow the user to try out different options easily
 Be easy to use
 Use suitable colours for key areas
 Use words that are easy to understand aimed at the type of user
 Have online help
It also should consider the needs of the users. For example, young children are likely to
prefer pictures to words and people with disabilities may benefit from particular input or
output devices

3. WIMP interface
 Windows, Icons, Menus and Pointer - a method by which a user can interact with
a computer without having to learn lots of special words - it provides a much
more intuitive 'view' of the computer and its facilities than non-WIMP operating
systems provide
 "Windows, /images/, Menus and Pointer", or "Windows, /images/, Mouse and
Pull-down menus" This is a graphical interface which makes access to computers
much more straightforward and intuitive than the main alternative, the command-
line interface. The WIMP interface has been used on Apple Macintosh computers
since they were invented, and are coming into use on PCs through Microsoft
Windows and on Unix and other workstations through the X Window system.
4. Menu driven interfaces
The user is offered a simple menu from which to choose an option. One menu often
leads to a further menu. Part of the screen may have an instruction followed by a
numbered list of options to choose from:
A full screen menu takes up most of the screen.
A menu bar is the set of options at the top of the screen. When an option is chosen a pull
down menu may be offered.
Features of menu driven interfaces include:
 They are easy to use as the user does not have to remember sets of commands.
 They are user friendly - you can often guess your way around the options.
 They can be irritating if there are too many levels of menus to move around - with
a command line interface you can go to the option required immediately.
USER INTERFACE
 A user interface is part of the systems software.
 People need a way of interacting with machines such as computers, notebooks, mobile
phones, cash machines (ATMs) etc.
 A user interface is the software that enables a user to provide instructions to, interact with
and control a computer or device e.g. a mobile phone.
 The user interface is often part of the operating system.
A user interface is a point of interaction between a computer and humans; it includes any
number of modalities of interaction (such as graphics, sound, position, movement...)
where data is transferred between the user and the computer system.

MS DOS VS WINDOWS
TOPIC COMMAND LINE (CLI) or DOS GUI or Windows OS
Ease
Due to a higher degree of memorization and
familiarity needed for operation and navigation,
new users find operating a command line interface
more difficult than a GUI.
Because a GUI is much more visually
intuitive, new users almost always pick up
this interface faster than a CLI.
Control
Users have more control over both the file and
operating systems in a command line interface. For
example, users can copy a specific file from one
location to another with a one-line command.
Although a GUI offers ample access to the
file and operating system, advanced tasks
may still need to utilize the command line.
Multitasking
Although many command line environments are
capable of multitasking, they do not offer the same
ease and ability to view multiple things at once on
one screen.
GUI users have windows that enable a user to
view, control, manipulate, and toggle through
multiple programs and folders at same time.
Speed
Command line users only need to utilize their
keyboards to navigate the interface. Additionally,
they often only need to execute a few lines to
perform a task.
Using both a mouse and keyboard to navigate
and control your operating or file system is
going to be much slower than someone who
is working in a command line.
Resources
A computer that is only using the command line
takes a lot less of the computer's system resources
than a GUI.
A GUI requires more system resources
because of the elements that require loading,
such as icons and fonts. Video, mouse, and
other drivers need to be loaded, taking up
additional system resources.
Scripting
A command line interface enables a user to script a
sequence of commands to perform a task or execute
a program.
Although A GUI enables a user to create
shortcuts, tasks, or other similar actions, it
doesn't even come close in comparison to
what is available through a command line.
Remote
access
When accessing another computer or device over a
network, a user can only manipulate the device or
its files with a command line interface.
Although remote graphical access is possible.
Not all computers and network equipment
has this ability.
Diversity
After you've learned how to navigate and use a
command line, it's not going to change as much as a
new GUI. Although new commands may be
introduced, the original commands always remain
the same.
Each GUI has a different design and structure
when it comes to performing different tasks.
Even different iterations of the same GUI,
such as Windows, can have hundreds of
different changes between each version.
Strain
The command line allows the user to keep their
hands on the keyboard, almost never touching the
mouse. Moving back and forth between a keyboard
and mouse can cause additional strain and may help
contribute to Carpal Tunnel Syndrome.
Although shortcut keys can help reduce the
amount of times you have move from the
keyboard to the mouse, you will still be
moving much more between devices in a
GUI.
Note: Although it appears that using the command line wins this comparison, it is beneficial for user know how both methods work as
they excel in different areas.

APPLICATION PACKAGES/SOFTWARE
 Are programs that are or were developed to solve specific user problems?
 Software application packages can be custom built or they can be bought off the
shelf.
 Application software consists of programs designed to perform specific tasks for
users. Application software can be used as a productivity/business tool; to assist
with graphics and multimedia projects; to support home, personal, and
educational activities; and to facilitate communications. Specific application
software products, called software packages, are available from software
vendors. Although application software also is available as shareware, freeware,
and public-domain software, these usually have fewer capabilities than retail
software packages.
Typical software applications that you might use are:
 Word processors, for example, Microsoft Word or the free Open Office Writer
 Spreadsheet software, for example, Microsoft Excel or Open Office Calc
 Graphics software, for example, Microsoft Paint, Adobe Photoshop, Corel Paint shop
Pro
 Web design software, for example, Adobe Dreamweaver
What is the difference between systems software and applications software?
System software controls how the computer system works and it enables the user to
access the system hardware and application software. Applications software does not
control the system; instead it allows the user to perform everyday tasks such as creating a
document or webpage.
# APPLICATION
SOFTWARE
DESCRIPTION EXAMPLES
1 Word processing
software
 A word processor is used to produce documents such as letters, memos and
reports. The latest versions of word processing software contain many
features and can also be used for "desktop publishing" to create newsletters,
brochures, business cards, signs and more. The latest word processing
software will allow you to easily type into columns, add pictures and charts
to your page, create custom borders, and experiment with a variety of
typefaces (fonts) in a wide range of sizes. You can even combine different
fonts on the same page.
 Word processing software offers many exciting formatting and editing
features to make your work easier. You can easily check the spelling of a
word or the entire document. The built in thesaurus will help you find an
alternate word to use. Blocks of text can be easily moved, copied or erased.
 Use this kind of tool to create worksheets, type letters, type papers, etc., e.g.
MS Word, WordPerfect,....
 Ms word,
Word
perfect,
Word star,
 Ms works
word
processor
,WordPro

2 Spreadsheet
software
 A spreadsheet is used to manage, analyze and present numeric information.
Some common uses of spreadsheet software are financial reports, personal
finances and business finances. Spreadsheet programs can also create a
chart from the numeric data.
 The working screen is laid out in rows and columns, much like a ledger.
The information is typed into a "cell." A cell is the intersection of a row and
a column. The cell can contain a number, a word or phrase (generally used
to identify what the number represents, such as a column or row heading),
or a math function or formula.
 Spreadsheets allow you to use simple math expressions such as add,
subtract, multiply or divide, or advanced math such as the type of
calculations performed by architects, engineers, economists and scientists.
Spreadsheets also have a special group of built-in formulas, called functions
that let you perform calculations without having to type long, complex
formulas. Functions are grouped into categories, such as financial,
statistical, engineering, logical, math and trigonometry, database and list
management, date and time, and information.
 Ms Excel,
 Quattro Pro,
 Lotus 1-2-3
3 Database
Management
Software
 Allows user to prepare reports based on data found in different records.
DBMS is an important managerial decision support tool for managers at all
levels of the organization. A database is an organised store of information,
for example an address book, list of employees, list of students, customers
or items of assets. Database package is used to store records. Data can be
sorted or filtered for separate viewing. Also Calculations and comparisons
between data items can be done. Popular database packages are: Microsoft
Excel, lotus Approach, Paradox, dBase IV, Data Ease.
 Use this software to store data such as address, membership and other text
information. A database can be used to easily sort and organize records
 Ms Access,
DbaseIV,
Oracle
4 Payroll  Payroll software is technology that aims to streamline and automate the
process of paying a company's employees.A payroll system calculates the
amount you owe your employees based on factors such as the time they
worked, their hourly wages or salaries, and whether they took vacation or
holiday time during the pay period. The system adjusts gross pay by
calculating and subtracting taxes and other withholding amounts.
 Pay plus ,
Pay well
5 Accounting  Accounting software describes a type of application software that records
and processes accounting transactions within functional modules such as
accounts payable, accounts receivable, payroll, and trial balance. It
functions as an accounting information system. It may be developed in-
house by the organization using it, may be purchased from a third party, or
may be a combination of a third-party application software package with
local modifications. Accounting software may be on-line based, accessed
anywhere at anytime with any device which is Internet enabled, or may be
desktop based. It varies greatly in its complexity and cos
 Pastel,
Tetra 2000
e.g. Pastel,
TurboCash,
QuickBooks
6 Presentation
graphics software
 Lets users or managers prepare slides containing charts, text and images.
Presentation graphics software usually provides libraries of clip art images
that can be cut and pasted into a slide to make the slide more attractive and
informative. These are applications designed solely for designing graphs
and text charts/posters and often used to produce slides for use on overhead
projectors, or presentations on computer-projectors. They can also produce
various types of charts. Examples of graphics packages are: Microsoft
PowerPoint, Lotus Freelance, Harvard Graphics and Corel Draw,
HyperStudio, Flash, Director.
 Use this software to create multimedia stacks of cards/screens that can
effectively present a lesson or a sales pitch. The user often clicks on buttons
to advance to the next screen in a sequence
 Ms
PowerPoint,
Lotus
freelance
graphs

7 Desktop
Publishing
 Use this software to make signs, banners, greeting cards, illustrative
worksheets, newsletters, etc
 Desktop Publishing (DTP) applications give users powerful and versatile
page design capabilities. The user can incorporate text and graphics on very
exact page layouts. These applications produce magazines, catalogues,
invitation cards, business cards and other sophisticated documents. It links
up well with other applications as the user can import text and graphics
from the other applications. Examples of DTP packages are: Microsoft
Publisher, PageMaker, Ventura and Frame maker.
 Ms
publisher,
Aldus
8 Multimedia Internet Browsers
 This software allows one to surf the Web. Often they can read email
and create Web pages too, e.g. Netscape Navigator (or Netscape
Communicator), MS Internet Explorer, AOL Browser....
Email programs
 These programs send and receive email, e.g. Netscape Messenger (part
of Netscape Communicator), MS Outlook Express, MS Outlook,
Eudora, AOL browser (has email built in)....
Graphics Programs (pixel-based)
 This software allows one to touch up photographs and create graphics
from scratch, e.g Adobe Photoshop, Paint Shop Pro, MS Paint (comes
free on Windows PC's), Painter, ....
 Internet
explorer
Netscape
9 Communication  This software allows two computers with modems to communicate through
audio, video, and/or chat-based means, e.g. MS NetMeeting, AOL Instant
Messenger, IRC, ICQ, CU-SeeMe, ...
 Ms
Outlook,
Ms
Exchange
10 Design  AutoCAD,
CAM
 e.g.
AutoCad,
Corel Draw
Different Common types of Applications
There can be huge numbers of applications available today and these applications are
classified into the following major types.
1. Productivity Softwares
2. Collaborative Softwares
3. Utility Softwares
4. Specialized Softwares
Productivity Softwares
These softwares are used to do special productive tasks for users such as writing
documents, managing personal information, giving presentations, storing data, and

sending e-mail. The following Table shows different kinds of productivity softwares,
their purposes and their examples.
Table: Different types of Productivity softwares
Collaborative Softwares
Collaborative softwares help people communicate and work with one another, and it
helps computers share information. The following table lists the collaboration software
types, their purpose and examples.

Table: Different types of Collaborative Softwares
Utility Software
Utility softwares are basically not in the Applications category because these don’t do
anything directly for the users using computers. Instead, utilities help keep the computer
running smoothly and help manage and distribute files. The following table shows
different types of utility softwares, their purposes and examples.

Table: Different Utility Softwares
Specialized Softwares
These applications are designed to do specific tasks for specific peoples. These can
include software for people in professions such as computer-aided design (CAD),
medicine, science, and finance, as well as games and entertainment applications. The
following Table shows different kinds of specialized softwares, their purposes and their
examples.
Table: Different types of Specialized softwares
This was all about the application platforms and application types and their uses with
examples. I hope that you have enjoyed the reading.

Advantages of using a word processor (e.g. MS Word) rather than a manual
typewriter
 Ability to correct mistakes
 Ability to view documents on screen before printing
 Ability to incorporate diagrams
 Ability to move parts of text to other sections of the document.
 Ability to save or store documents for future reference or use.
 Ability to alter or change document layout.
 Ability to print a lot of copies [ no retyping]
 Ability to insert tables
 Ability to format document [font, paragraphs, bullets etc] Spelling and grammar
checker
 Import files
 Mail merge
 WYSIWYG capability
 Creation of templates
 Automatic creation of index and table of contents
a) Explain what is meant by the term ‘word processing package’.
 Is a program or set of programs used to enter, edit, format, store and
print documents. A document may be anything from a single memo to
a complete book.
 An application package that involves the use of computers to
manipulate text data in order to produce office communications in the
form of documents.
 Any of many popular application programs designed for composing,
revising, printing, and filing written documents.
 Word Processing is the efficient and effective production of written
communications at the lowest possible cost through the combined use
of systems management procedures, automated technology, and
accomplished personnel. The equipment used in word processing
applications includes but is not limited to the following: dictation and
transcription equipment, automatic repetitive typewriters, visual
display text editing typewriters, keyboard terminals, etc.
b) Give any 2 examples of a word processing package’.
 Ms Word
 Word Star
 Word Perfect
 Ms Works Word
c) Briefly describe any 5 important features of a word processor.
1) Spelling and grammar checker

2) Import files
3) Mail merge
4) WYSIWYG capability
5) Creation of templates
6) Automatic creation of index and table of contents
d) List any 10 facilities that spreadsheets offer.
1. Format cells, rows and columns, specifying for example, the alignment of text,
number of decimal points, height and width of a cell.
2. Copy cell contents to other locations
3. Determine the effect of several different hypothetical changes of data
4. Insert, move or delete rows and columns
5. Use functions such as SUM, AVERAGE, MAX, MIN in formulae
6. Create a simple database and sort or query the data to produce a report
7. Write macros to automate common procedures
8. Create templates i.e. spreadsheets with formats and formulae already entered, into
which new figures may be inserted.
9. Create multi-dimensional spreadsheets using several sheets, and copy data from one
sheet to another
10. Create many different types of charts and graphs
Criteria for Selecting Applications Software:
 Accuracy - it must be free from errors
 Flexibility – it must be able to adapt to changing environment.
 Compatibility - it must be compatible with available hardware and software
 Recency - it must be current
 Cost - it must have reasonable cost
 Originality - It must be original
 Support - consider continued support from the supplier.
 Ease of use - it must be user friendly.
 Performance - it must have efficiency in both response time and run time.
 Memory requirements
FACTORS TO CONSIDER WHEN BUYING APPLICATION SOFTWARE
1. Cost. This includes the original cost of the package, technical support, and
upgrades.
2. Portability, can it be installed on one type of hardware or a variety
3. Relevance of the software to the task at hand.
4. Compatibility with existing hardware & software. Will the package run on
existing hardware? Can files be easily transferred from existing systems without
re-keying? Can files created in the package be exported to other systems in use in
the company?
5. It should be on a media compatible with your computer i.e. if you purchase
software on CD media your computer should have compact disk drive.

6. Sophistication, simple programs are usually easy to learn, cost less and are
appropriate for those who use the software infrequently.
7. Should include enough documentation such as installation instructions, system
requirements e.g. Pentium 4, reference manual, registration information, supplier
details and user manual.
8. Standard software, which is well supported locally i.e. used by most people in
that area
9. Is the application upgradeable and does it support future upgrades.
10. Easiness of installation
11. Technical support. Is support available? Is it very costly? Often, technical
support contract can add 50% or more to the price of a package, but without it no
support at all will be given by the manufacturer.
12. Easy of learning. Are tutorials supplied? Are books on the software available in
bookshops? Are training courses available?
13. Easy of use and user- friendliness. Is it easy to use, for example using pull
down menus, icons, helpful error messages when you do something wrong?
14. Is the application from a reputable supplier e.g. Microsoft.
15. Do you have enough resourceson your PC to install it e.g. it may require
256MB RAM, 80GB HDD. Memory requirements; software packages vary in
the amount of memory they require. Will the system require expenditure on more
powerful hardware?
16. Does the version of the product that I am considering run on my
personalcomputer system? Is it compatible with my platform (PC, Macintosh,
Sun, and so on)? with the processor used in my computer (486, Pentium,
Motorola 6040, PowerPC, and so on)? and with the operating system that I am
running (DOS, Windows, NeXT Step, UNIX)?
17. Is the product compatible with other programs, such as extensions and device
drivers, that I have on my personalcomputer system?
18. Does the product do all that I want it to do? Is it simple enough to use
immediately but powerful enough to provide the capabilities that I will want as
my familiarity with the program increases?
19. Is the product an up-to-date, current version or release?
20. Does the product have a clear, step-by-step tutorial? Is the product easy to
learn?
21. Is the product accompanied by clear, easy-to-follow instructions, or
documentation?
22. Does the manufacturer provide technical assistance? Is a toll-free technical
assistance number included in the software documentation? Does the
manufacturer have a bulletin board or Internet address for technical assistance
questions? Does the manufacturer charge for technical assistance? for product
revisions or upgrades?
23. Can I find instruction, or training, in the use of the product?
24. Is the product from a respected, well known manufacturer?
25. Does the program have any known problems, or bugs, and will these affect my
use of the program?

26. Does the product come with a warranty, and what are the conditions of that
warranty?
27. Does the product cost more or less than comparable products on the market?
Benefits of application software to the user.
 Installation should be easy, quick and should be provided by the
vendor/supplier.
 Good documentation is usually provided with the application for reference
purposes.
 Onsite assistance from the supplier or vendor
 Provision of cheaper future upgrades upon acquisition of an application
provided you have completed the registration information.
 Value for money
Applications software comes in different 'flavors' - or types:
 Utility programs - these can be part of an operating system, but are also
available for separate purchase. Examples include virus checkers, disk
defragmenters, back up utilities and disk checker software.
 Generic - general purpose software that is not written for any particular type of
business. Examples of this include word processors and spreadsheets.
 Integrated - a collection of software that has a common set of commands/icons.
Usually they include word processors, spreadsheets and graphics software, but
they can contain databases as well. They tend to be cheaper than purchasing each
application separately.
 Specific - software written for a defined purpose. Accountancy software is a good
example of this, and can be bought by anyone.
 Bespoke - also known as 'tailor made'. A company may need a particular piece of
software that it cannot purchase because it does not exist yet - or it does not like
what is available. The company can commission the software to be specially
written for them. This tends to be expensive.
SOURCES OF APPLICATION SOFTWARE
1. Freeware
 Freeware is the type of freely available software whose developer decides to distribute it for free.
In contrast to the open source software, the source code in this case is not available for
modifications and further development. Also, it should be noted that the distribution of the
software may also be restricted by its developer, often allowing users to download it from his site
only. Many free to download applications are available on the Internet. It is always wise to read
the license before downloading the software. Many people tend to unknowingly share such
applications with other people, without realizing that this may actually be illegal.
2. Open source software
 Is computer software with its source code made available with a license in which the copyright
holder provides the rights to study, change, and distribute the software to anyone and for any
purpose.
3. Shareware

 Shareware is very different from these other forms of free software and to some extent also a
misnomer. The authors of shareware maintain their full intellectual right over shareware. The only
difference between shareware and other commercially available software is that in this case the
software is available for freely for trial for a limited number of days, or a limited number of times.
After the expiry of the ‘free’ period, the users of shareware are required to pay for it. Source code
and collaboration communities which exist around open source projects do not exist in this case.
4. Off-the –shelf/generic or Commercial Software
 This is software that can be purchased, from a software company that develops programs and sells
them too many computer users and organizations. Applications such as financial accounting,
business graphics and pay roll may be bought.
o These are bought from a vendor
5. In-house/Custom made/Tailor Made/Bespoke software
 Customized software is software designed around a company or other organization's processes to
make those processes more efficient.
 It is distinct from market software [commercial or generic], which approaches problems in a
general way so that the product can be sold to more than one customer.
 Has been written by the vendor specifically for a user’s needs. Also known as in-house packages,
tailor-made packages.
6. Outsourcing
This involves contracting out software development to a software house - better known as
outsourcing, especially where off-the-shelf packages are not available.
Advantages
o Software houses employ professionals and this may benefit the organisation
o Transfer of skills to the existing professionals in an organisation
o Organisation can get support from the contractor.
Disadvantages
o There could be breach of confidentiality.
o Contractor may go bankrupt and cease trading leaving the user with no support.
o Contractor might not have sufficient experience or understanding of the problem; thus the
solution might not be satisfactory.
o It takes time for the contractor to understand the user's business and operations, which
makes the approach expensive.
CLASSIFICATION OF SOFTWARE APPLICATIONS
1. Commercial / generic Packages/Off the shelf software
 Commercial software is computer software sold for profit; such software
represented, until recently, the vast majority of all software used.
 These are bought from a vendor.
 Also known as off the shelf packages e.g. MS Office, Pastel.
 Also known as work enhancement applications
 Generic or Off the shelf software has the advantage of cost effectiveness
due to larger market & the ability to incorporate available technology in
the shortest possible time.
These increase the productivity & efficiency in the work place i.e.
o Word Processing packages
o Spreadsheet packages

o Database /Information retrieval Packages
o Graphics packages
o Data communications Software
 Off-the –shelf/generic or Commercial Software
This is software that can be purchased, from a software company that develops
programs and sells them to many computer users and organizations. Applications
such as financial accounting, business graphics and pay roll may be bought.
Advantages
o Cheaper - the software company is able to spread the software development
cost over a large number of customers, hence reducing the cost any one
customer must pay.
o Less risky - the software is in existence, hence you can analyse the features
and performance of the package.
o The program is a well-tried and tested product with few errors.
o Less time - Off-the -shelf software is often installed quickly and easily.
o The package is well documented
o The packages require little maintenance
o There is continued support from the supplier through upgrades.
o It is cheaper than custom-written software. The development costs of the
package may be millions of pounds, but the customer may be able to buy it for
a few hundred pounds, since sales are made to thousands of other customers.
o It is immediately available and already thoroughly tested so is unlikely to have
major bugs in it
o Documentation is usually available in the form of reference manuals, user
guides and tutorials
o Training courses may be available form third party trainers.
o Technical support is usually available from the manufacturers via a Web site
or telephone line [at a price].
o Other users of the package can be consulted as to its suitability before
purchase.
o Upgrades are usually available every year or two
Disadvantages
o The package may not do exactly what you want it to do;
o It may not run on the firm’s existing hardware
o It may not interface with other software already in use in the
organization.
o The organization might need to pay for the features that are not
required and never used.
o The package may be for general needs and therefore not ideal for the
user.

o The user has no direct control over the package,
2. Homemade / Customized packages/ Tailor-made Software
 Customized software is software designed around a company or other
organization's processes to make those processes more efficient.
 It is distinct from market software [commercial or generic], which
approaches problems in a general way so that the product can be sold to more
than one customer.
 Has been written by the vendor specifically for a user’s needs. Also known as
in-house packages, tailor-made packages.
 E.g. most payroll packages, billing software, product design applications
 Is that application that has been written for a specific user’s needs by a
software vendor?
 It is non-standard software.
 In-house/Custom made/Tailor Made/Bespoke software
This approach requires a development team from within the organisation. The
team is usually comprised of programmers and analysts. The team members
should be of high calibre, highly trained and reliable.
Advantages
o Internal professionals understand operations better and therefore can
produce an accurate solution.
o The Software usually meets user requirements.
o Management are in total control of the development process
o More flexibility - there is more flexibility in making modifications.
o Problem specificity - in-house developed software can give an
organisation software programmes that are easily tailored to a unique
problem or task.
Disadvantages
 Time and costs of developing the program may be greater than other
options
 In-house staff may lack the expertise needed for the project
 Reliability of the resultant software is highly questionable.
 In some cases the developers may attempt to gain fraudulently from the
system

Disadvantages
1. Being customized, the non-standard software may not be used by any other
organization.
2. It has huge support costs after implementation.
3. Dependency syndrome with the supplier. There is heavy reliance on the
developers of the software for its continued existence & maintenance

4. Future support may be difficult if the supplying company goes under, shuts down,
or liquidate or if its development staff leaves.
5. May not be upgradeable and may not run if moved to a new hardware platform.
6. You are tied to a supplier of which you may not be willing to have a maintenance
contract with.
7. Written or Custom-built software performs a defined function and is expensive
to build.
8. Custom built is expensive to maintain
9. Custom built software has reduced lifespan due to high speed of technological
advancement in the field of computers.
UTILITY SOFTWARE
Utility software (also known as service program, service routine, tool, or utility routine)
is computer software designed to help manage and tune the computer hardware, operating
system or application software by performing a single task or a small range of tasks.
Some utility software has been integrated into most major operating systems.
Examples
 Disk storage utilities
o Disk defragmenters can detect computer files whose contents are broken
across several locations on the hard disk, and move the fragments to one
location to increase efficiency.
o Disk checkers can scan the contents of a hard disk to find files or areas
that are corrupted in some way, or were not correctly saved, and eliminate
them for a more efficiently operating hard drive.
o Disk cleaners can find files that are unnecessary to computer operation, or
take up considerable amounts of space. Disk cleaner helps the user to
decide what to delete when their hard disk is full.
o Disk space analyzers for the visualization of disk space usage by getting
the size for each folder (including subfolders) & files in folder or drive.
showing the distribution of the used space.
o Disk partitioners can divide an individual drive into multiple logical
drives, each with its own filesystem which can be mounted by the
operating system and treated as an individual drive.
o Backup utilities can make a copy of all information stored on a disk, and
restore either the entire disk (e.g. in an event of disk failure) or selected
files (e.g. in an event of accidental deletion).
o Disk compression utilities can transparently compress/uncompress the
contents of a disk, increasing the capacity of the disk.
o File managers provide a convenient method of performing routine data
management tasks, such as deleting, renaming, cataloging, uncataloging,
moving, copying, merging, generating and modifying data sets.
o Archive utilities output a stream or a single file when provided with a
directory or a set of files. Archive utilities, unlike archive suites, usually
do not include compression or encryption capabilities. Some archive

utilities may even have a separate un-archive utility for the reverse
operation.
 System profilers provide detailed information about the software installed and
hardware attached to the computer.
 Anti-virus utilities scan for computer viruses.
 Text and Hex Editors directly modify the text or data of a file. These files could
be data or an actual program.
 Data compression utilities output a shorter stream or a smaller file when
provided with a stream or file.
 Cryptographic utilities encrypt and decrypt streams and files.
 Launcher applications provide a convenient access point for application
software.
 Registry cleaners clean and optimize the Windows registry by removing old
registry keys that are no longer in use.
 Network managers check the computer's network, log events and check data
transfer.
 Command line interface (CLI) and Graphical user interface (GUI) Allows the
user to contact and make changes to the operating system.
INTEGRATED SOFTWARE
 Integrated software is software for personal computers that combines the most
commonly used functions of many productivity software programs into one
application.
 The integrated software genre has been largely overshadowed by fully functional
office suites, most notably Microsoft Office, but at one time was considered the
"killer application" type responsible for the rise and dominance of the IBM PC in
the desktop business computing world.
 In the early days of the PC before GUIs became common, user interfaces were
text-only and were operated mostly by function key and modifier key sequences.
Every program used a different set of keystrokes, making it difficult for a user to
master more than one or two programs. Programs were loaded from floppy disk,
making it very slow and inconvenient to switch between programs and difficult or
impossible to exchange data between them (to transfer the results from a
spreadsheet to a word processor document for example). In response to these
limitations, vendors created multifunction "integrated" packages, eliminating the
need to switch between programs and presenting the user with a more consistent
interface.
 The potential for greater ease-of-use made integrated software attractive to home
markets as well as business, and packages such as the original AppleWorks for
the Apple II and Jane for the Commodore 128 were developed in the 1980s to run
on most popular home computers of the day.
 Context MBA was an early example of the genre, and featured spreadsheet,
database, chart-making, word processing and terminal emulation functions.

However, because it was written in Pascal for portability, it ran slowly on the
relatively underpowered systems of the day. Lotus 1-2-3, which followed it, had
fewer functions but was written in assembler, providing it with a speed advantage
that allowed it to become the predominant business application for personal
computers.[2]
 The integrated software market of today is exemplified by entry-level programs
such as Microsoft Works which are often bundled with personal computers as
"starter" productivity suites.
SOFTWARE SUITES/BUNDLED SOFTWARE
 A software suite or application suite is a collection of computer programs, usually
application software and programming software of related functionality, often
sharing a more-or-less common user interface and some ability to smoothly
exchange data with each other.
 Sometimes software makers introduce "suites" that are little more than
repackaged versions of older programs offered at a lower price.
 The solution might be "software suites" or "bundled software." A "suite" is a
collection of the full-featured versions of each software application - word
processing, spreadsheet, database management, graphics, communications and
sometimes organizers.
 These applications are from the same software manufacturer and are packaged
together in a large box and sold at prices that are much lower than if they were
purchased individually - usually less than half of the original collective price! The
software applications contained in a suite or bundle are the same applications a
professional user might purchase individually. No corners have been cut, and
additional features may have been added such as a "common interface" that
allows any of the programs to be accessed from the same "main menu," a
consistent screen layout used by each of the programs, and the ability to easily
exchange data from one program to another.
INTEGRATED SOFTWARE/BUNDLED SOFTWARE / SOFTWARE SUITE
 SOFTWARE that contains several applications rolled into one. Integrated
software usually includes word processing, spreadsheet, database, graphics
and communication capabilities. Two popular Integrated software packages
are Microsoft Works and ClarisWorks:
 In integrated software, you will be able to work on a spreadsheet to perform
calculations, store addresses and phone numbers in a database and be able to link
information from the spreadsheet & the database when you work with the word
processor in the integrated package.
 Object Linking Embedding [OLE] is a standard that, Allows applications to be
linked together.
 OLE-DB allows applications to import virtually any form of data into the
database.

integrated software
 A group of applications designed to work together and share data easily.
Software that combines the features of several different applications in a single
program (e.g. word processing, database, spreadsheet, graphics, and
communications)..
Advantages of integrated applications
 Easy to use
 Generally costs much less
 Require or needs less RAM
 Ability to pass data from one module to another.
 Takes up much less hard disk space
 Better organization of information. Data is stored in the database, calculations in
an electronic spreadsheet & images in a graphical application package
The advantages of bundled software suites are
 Low cost compared to buying each application separately
 Option to install all of the programs at the same time or only the programs you
want to use
 Consistent interface from one application to another
 The ability to share information between applications
 Future upgrades can update each application all at the same time
 Ideal for personal use, professional use, large or small business
 Each application is the full-featured version
The disadvantages are
 High initial cost
 All applications are from the same manufacturer - you might prefer a word
processor from one company, a spreadsheet from a different manufacturer, etc.
 May be purchasing more software than you actually need
 Installation of the entire suite of applications takes up a large amount of storage
space on your internal hard disk
 Several large manuals to study if you plan to master each application, or the
package might not include printed manuals in order to keep the cost low
Disadvantages
 Limited portability. The same applications must exist on every computer that you
wish to open the document.
 Offer fewer features and less versatility than stand alone versions or software.
 Functional limitation. Its rigid you cannot change it to suit your specific needs.
EXAMPLES OF INTEGRATED SOFTWARE

 Microsoft Office 97
 Microsoft Works
 Claris Works
 Lotus SmartSuite 97
 Microsoft Office 2003,2007,2010 & 2013
OPEN SOURCE SOFTWARE
 Open source is a type of software which is freely available and its source code is
available for further development, modification. Generally all open source
software have a community of developers who provide support, documentation
and even binary versions of the software to people who may be interested in it.
These additional services, though, may not be free monetarily.
 There are several ongoing open source software projects. The open source nature
of these projects means that there will be several people working on modifying
and improving the software from around the world. Some such examples include
the Web browser Mozilla Firefox, content management software like Drupal,
Joomla etc.
SOFTWARE COPYRIGHT
The Copyright, Designs and Patents Act
Copyright is a legal concept, giving the creator of an original work exclusive rights to
control its distribution for a certain time period.
Copying computer software is therefore a breach of copyright and a criminal offence. The
Act covers stealing software, using illegally copied software and manuals, and running
purchased software on more machines than the license allows.
The legal penalties for breaking the copyright law include unlimited fines and up to two
years in prison.
All the software that you use should be fully licensed. When you purchase software you
usually are licensed to use it on just one computer. It is illegal to make copies of the
software to use on other computers, even if they are your own.
Software licences can be:
 Single user - licensed for installation on one computer
 Multi-user - the license allows you to install the software on a named number of
computers
 Site-licence - the licence lets you install the software onto an unlimited number of
computers, as long as they are on one distinct site such as a school

Software protection
Software companies try to prevent illegal copying of their disks using the following
methods:
 Copy protection - the disk (or CD-Rom) may be formatted in a special way so it
cannot easily be copied.
 Restricting the number of installations - each installation is recorded on an
installation disk and only a certain number are allowed.
 A registration key - a unique series of letters and numbers that is asked for when
running the program. The software will not run if the registration key is not typed
in correctly and online multiplayer games will not to run if another user is online
who has used the same key.
 A phone or Internet activation code - this requires the user to call a number or
go online to register the product. They then receive a unique computer-specific
serial number.
 Encryption - data can be scrambled up and cannot be read without the correct
software.
 A Dongle - a piece of hardware that must be plugged into the computer to run the
software. Each one contains a unique electronic serial number and as they are
expensive to produce they are mostly used to protect high-end software packages.
 Details of the user are built into the software - when the software is run it
displays the original users name. This does not prevent the copying but it makes is
obvious that the copy is illegal.
 A Keyfile - a small file with a unique code that is placed in the same directory as
the program. If the code is not valid then the software will not run.
SOFTWARE PIRACY
 Unauthorized copying of software.
 Unauthorized use or reproduction of copyrighted patented material.
 unauthorized copying of software
 The production of illegal copies of software.
 By far, the biggest legal problem affecting the computer industry today is
software piracy, which is the illegal copying or use of programs. Piracy is a huge
problem mainly because it is so easy to do. In most cases, it is no more difficult
to steal a program than it is to tape a music CD that you have borrowed from a
friend. Software pirates give up the right to receive upgrades and technical
support, but they gain the use of the program without paying for it.
Implications of Software piracy
 Loss of business to software companies.
 Lack of technical support, no connection with supplier upgrades.
 Software incompatibility, may require a key, which you might not have, as a
result you can’t install it.
 Virus Spread
 Lawsuits for copyright, which may be very costly in terms of reputation and
money.

 Piracy harms all software publishers, Regardless of their size. Software
publishers spend years developing software for the public to use. A portion
of every dollar spent in purchasing original software is channeled back into
research and development so that better, more advanced software products
can be produced. When you purchase pirated software, your money goes
directly into the pockets of software pirates instead.
 Software piracy also harms the local and national economies. Fewer
legitimate software sales result in lost tax revenue and decreased
employment. Software piracy greatly hinders the development of local
software communities. If software publishers cannot sell their products in
the legitimate market, they have no incentive to continue developing
programs. Many software publishers simply won’t enter markets where the
piracy rates are too high, because they will not be able to recover their
development costs.
 Software piracy harms everyone in the software community including
you, the end user. How?
1) Piracy results in higher prices for duly licensed users,
2) Piracy reduces levels of support, and
3) Delays in the funding and development of new products, causing the
overall selection and quality of software to suffer.
THE DIFFERENT TYPES OF SOFTWARE PIRACY
There are five basic forms of software piracy, and all are damaging both to the software
publisher and to you, the end user. The five basic types of piracy are:
 Soft lifting. This form of piracy occurs when extra copies of a program are made
within an organization for employees to use. It also includes "Disk swapping" among
friends and associates.
 Hard-Disk Loading. Some computer dealers load unauthorized copies of software
onto the hard disks of the computers they offer for sale, as an incentive for an end
user to purchase a computer from that particular dealer.
 Counterfeiting. This is the illegal duplication and sale of copyrighted software, often
in a form designed to make the product appear legitimate. Software counterfeiting can
be very sophisticated, including significant efforts to replicate packaging, logos, and
anti-counterfeiting techniques such as holograms. It can also be unsophisticated,
consisting of inferior or hand-written labels, with disks folded into a plastic bag and
sold on street corners. A recent trend in counterfeiting is the emergence of
compilation CD-ROMs, where numerous unauthorized software publishers’ programs
appear on one CD-ROM. In any form, software counterfeiting is very damaging to
both the software developer and legitimate end users.
 Online. This form of piracy occurs when copyrighted software is downloaded to
users connected through a modem to an electronic bulletin board or the Internet
without the express permission of the copyright owner. This should not be confused
with sharing public domain software or providing “shareware.” Shareware is software
that may or may not be copyrighted but is generally offered for little or no charge by
the author for nearly unrestricted use, including copying or sharing with others.
Microsoft distributes promotional products, free software, updates, or enhancements

over bulletin boards or online services, which may or may not be licensed for use
solely with licensed Microsoft products. You should check the EULA accompanying
the product to determine how it can be used.
 License Misuse. This form of piracy occurs when copyrighted software is distributed
outside the restricted legitimate channels it was designed for or the product is used in
ways not allowed in the license agreement. Examples of license misuse include:
(1) Academic product misuse
This form of license misuse occurs when a product that is manufactured,
licensed, and specifically marked for distribution to educational institutions
and students at reduced prices is diverted into normal commercial channels of
distribution. Typically this product will contain a sticker indicating that it is
academic product and for use only by educational institutions.
(2) Not for Resale (NFR) product misuse.
Again, this form of license misuse occurs when a product that has been clearly
marked "Not for Resale," and is typically distributed as a promotional or
sample product and is not licensed for normal commercial distribution and
use, is diverted into normal commercial channels of distribution.
(3) Original equipment manufacturer (OEM) stand-alone product. This form
of license misuse occurs when OEM version software has been unbundled from
its designated computer system and distributed as a separate, “stand-alone”
product. Microsoft’s agreement with computer manufacturers prohibits them from
distributing Microsoft products in this fashion, i.e. without accompanying
computer hardware.
Microsoft products on the retail shelf should never include a line on the front
cover of the User’s Guide that states, “For Distribution Only With New Computer
Hardware.”
(3) “Microsoft Easy Fulfillment” (MEF) product misuse. This form of license
misuse occurs when a “Microsoft Easy Fulfillment” (MEF) product is diverted
into normal commercial channels of distribution. The MEF product may be
distributed only to end users who have a Select or Open (MOLP) license and
who order the product in accordance with their license terms. The MEF
product has a sticker on the jewel case identifying the product as “Microsoft
Easy Fulfillment.”
(4) Volume licensing misuse. Volume Licensing enables organizations to acquire
the rights to copy and use specific Microsoft software products with
agreements tailored to the number of products needed at the particular
organization. These volume programs offer a broad range of products and
licensing options and reduce administrative overhead and software
management costs.
Microsoft offers two types of volume license:
a. Select provides savings for medium and large organizations with significant
volume requirements through forecasting software needs over a two-year
period.

b. Open provides savings for small and medium organizations for licenses of as
few as 20 units of a particular software product, with a simple ordering
process.
Misuse under volume licensing occurs when organization copies software
purchased through the volume program on more computers than specified in their
license agreement. Other violations occur when an organization allows concurrent
use of software products (which currently is offered only as an option under the
Select and Open programs) without the purchase of the option that allows for this
concurrent use.
User licenses show users rights to use pieces of software.
INTRODUCTION TO DATABASE SYSTEMS
A DATABASE is a shared and integrated collection of logically related records or files
consolidated into a common pool that provides data for one or more uses.
 Is a collection of files?
 An organized collection of interrelated files.
 Is a collection of related files that provides a way of finding information quickly
and easily from a chosen reference point?
 Is an integrated collection of logically related records or files?
 A database consolidates records previously stored in separate files into a common
pool of data records that provides data for many applications.
 Examples of databases are MS Access, MS Works Database, and DBaseIV,
Oracle, SQL
Building Blocks of a Database System
BIT  BYTE  FIELD  RECORD  FILE  DATABASE
 A byte is also known as a character
 A field is also known as a word
 A file is also called a table or relation
 File-Is a collection of related records.
 Record-Is a collection of fields. It is a collection of fields arranged in a
predefined order.
 Field-Is a collection of single items. It is an implementation of the data
attribute. It is the smallest unit of data to be stored in a database.
 Primary key-Is a field whose value identifies one & only one record in a
file.

 Secondary key-An alternative index for identifying an entity. Its value
can identify single entity occurrences of all entity occurrences. A subset of
all entity occurrences.
 Foreign key-Are pointers or links to occurrences of a different file. A
foreign key in one file must be a primary key in another file.
 Descriptors-Are any other fields that describe business entities.
Traditional/Conventional/Flat Filing Systems
 This is programming with files. Each user defines and implements the files
needed for a specific application so that each application has its own separate data
files and software programs
 Although both users will be interested in the same data, each maintains separate
files and programs to manipulate these files and this results in data redundancy
and a lot other problems associated with it.
Advantages of the Database Approach
 Control over data redundancy
 Increased data consistency/Reduced data confusion
 Increased data integrity – concerned with validity and accuracy of data
 Reduction in wastage of storage space
 Program/Data independence
 Increased productivity of application development
 Improved data security
 Data sharing
Disadvantages
 Database systems are complex, difficult and time consuming to design
 There is greater impact of failure
 Extensive conversion costs involved
 Initial training is required for all users
 Concurrence problems - where more than one user access and attempt to update
the same record at the same time - there is file edit locking to prevent this.
 Ownership problems - sometimes some individuals tend to own the data and thus
refuse access by other individuals or departments in the organisation.
 Resources problem - with database extra resources are needed e.g. more
workstations and other devices. Substantial hardware and software startup costs
are involved
Security problems - there is increased exposure to unauthorised entry into the data.
However, this could be reduced by the use of regularly changed passwords and by
physically denying access to unauthorised users.

DATABASE TERMINOLOGY
 Entity - a real world object or event or anything that is capable of independence
existence and about which we can collect information e.g. person, building,
transaction, election
 Attribute – a characteristic or property of an entity e.g. name
 Primary key – an attribute that uniquely identifies an entity or record. A field
that uniquely identifies a record in a table. In a students table, for instance, a key
built from last name + first name might not give you a unique identifier (two or
more Jane Does in the school, for example). To uniquely identify each student,
you might add a special Student ID field to be used as the primary key.
 Foreign key - A key used in one table to represent the value of a primary key in a
related table. While primary keys must contain unique values, foreign keys may
have duplicates. For instance, if we use student ID as the primary key in a
Students table (each student has a unique ID), we could use student ID as a
foreign key in a Courses table: as each student may do more than one course, the
student ID field in the Courses table (often shortened to Courses.student ID) will
hold duplicate values.
 Normalization - The process of structuring data to minimise duplication and
inconsistencies. The process usually involves breaking down a single table into
two or more tables and defining relationships between those tables. The process
of breaking up a table into multiple tables, each of which has a single theme,
thereby reducing data redundancy; 2) The technique that reduces or eliminates the
possibility that a database is subject to modification anomalies
 Query - A view of your data showing information from one or more tables. For
example, you could query a Students database asking "Show me the first and last
names of the students who take both history and geography and have Alice
Hernandez as their advisor". Such a query displays information from the Students
table (firstname, lastname), Courses table (course description) and Advisor table
(advisor name), using the keys (student ID, course ID, advisor ID) to find
matching information. Literally, a question you ask about data in the database in
the form of a command, written in a query language, defining sort order and
selection, that is used to generate an ad hoc list of records; 2) The output subset of
data produced in response to a query.
 SQL - Structured Query Language (pronounced sequel or ess-queue-ell). A
computer language designed to organize and simplify the process of getting
information out of a database in a usable form, and also used to reorganize data
within databases.
 Relation - A single store of related information. A table consists of records, and
each record is made up of a number of fields. You can think of the phone book as
a table: It contains a record for each telephone subscriber, and each subscriber’s
details are contained in three fields – name, address and telephone.
 DBMS - Database management system. A program which lets you manage
information in databases. Microsoft Access is a DBMS, although the term is often
shortened to ‘database’. So, the same term is used to apply to the program you use
to organize your data and the actual data structure you create with that program.

 Domain - A collection or range of all the possible values a field can contain.
Although a field’s domain is typically finite, it may be infinite as well.
 Derived attribute - Synonymous with computed attribute, for which the value is
calculated from those contained in other fields. Usually, computed fields’ values
are calculated from other fields’ values that occur in the same record
 Metadata - Data about data and the data’s structure within a database. Technical
metadata reflects the description of the structure, content, keys, and indexes of
data and their source of origin, while business metadata reflects definitions about
measures (facts) using calculations
 OLAP - (Online Analytical Processing)The OLAP Council defines online
analytical processing as, "A category of software technology that enables
analysis, managers and executives to gain insight into data through fast,
consistent, interactive access to wide variety of possible views of information that
have been transformed from raw data to reflect the real dimensionality of the
enterprise as understood by the user."
 Record - Synonymous with row and tuple. An instance of data in a table, a record
is a collection of all the facts related to one physical or conceptual entity; often
referring to a single object or person, usually represented as a row of data in a
table, and sometimes referred to as a tuple in some, particularly older, database
management systems.
 Schema - The database’s metadata -- the structure of an entire database, which
specifies, among other things, the tables, their fields, and their domains. In some
database systems, the linking or join fields are also specified as part of the schema
2) The description of a single table. Also called a Logical Schema.
 Concatenated key – a key formed by joining two or more attributes
 Relationship a link or association between any two entities in a database
 ERD - An entity-relationship (ER) diagram is a specialized graphic that illustrates
the interrelationships between entities in a database. ER diagrams often use
symbols to represent three different types of information. Boxes are commonly
used to represent entities. Diamonds are normally used to represent relationships
and ovals are used to represent attributes.
TYPES OF DATABASE RELATIONSHIPS
One-to-One
o Exactly one record in one table is related by a common linking field to exactly one
record in another table, implying that each value of the linking field appears no
more than once in each of the tables. Both tables can have only one record on either
side of the relationship. Each primary key value relates to only one (or no) record
in the related table. They're like spouses—you may or may not be married, but if
you are, both you and your spouse have only one spouse. Most one-to-one
relationships are forced by business rules and don't flow naturally from the data. In
the absence of such a rule, you can usually combine both tables into one table
without breaking any normalization rules.

One-to-Many
o Exactly one record in one table is related by a common linking field to one or more
records in another table, implying that each value of the linking field is unique in
the first table, but not necessarily so in the second. The primary key table contains
only one record that relates to none, one, or many records in the related table. This
relationship is similar to the one between you and a parent. You have only one
mother, but your mother may have several children.
Many-to-Many
 One or more records in one table may be related to one or more records in a
second table by a common value or linking (join) field. This implies that each
value of the linking field may appear any number of times in either or both tables.
Each record in both tables can relate to any number of records (or no records) in
the other table. For instance, if you have several siblings, so do your siblings
(have many siblings). Many-to-many relationships require a third table, known as
an associate or linking table, because relational systems can't directly
accommodate the relationship.
The Database Administrator
This is a person responsible for planning, designing and maintaining the organisation's
database. This person relates to the management, system analysts, programmers and other
stakeholders in the organisation. He needs to have adequate managerial and technical
abilities to suit the job. He therefore must have a sound knowledge of the structure of the
database and the DBMS.
Responsibilities of the Database Administrator (DBA)
 Ensures that the database meets the needs of the organisation.
 Ensures facilities for the recovery of data
 Ensures the functioning of report generation systems form the DBMS
 The DBA is also responsible for the documentation of the DBMS through the
designing and availing of the data dictionary and manuals for the users giving
such direction as the general use of the database, access to information, deletion
of records from the system and the general validation and verification of data.
 The design of the database
 After the initial design, the DBA must monitor the performance of the database,
and if problems surface (such as a particular report taking an unacceptably long
time to produce), appropriate changes must be made to the database structure.
 Keeping users informed of changes in the database structure that will affect them;
for example, if the size or format of a particular field is altered or additional fields
added
 Maintenance of the data dictionary for the database, and responsibility for
establishing conventions for naming tables, columns, indexes & so on.

 Implementing access privileges for all users of the database; that is, specifying
which items can be accessed and / or changed by each user.
 Allocating passwords to each user.
 Providing training to users in how to access and use the database.
 Manage the organizations
 -data resources
 -database plans
 -design
 -operations
 -training
 -user support
 -security & Maintenance
 Maintain data consistency and security
 Approve access to data stored
 Approve access procedures
 ABILITY to delete, add, modify –existing data must be tightly controlled.
Database Management System (DBMS)
The DBMS is an application program that provides an interface between the operating
system and the user in order to make access to the data as simple as possible. It has
several other functions as well, and these are described below.
1. Data storage, retrieval and update. The DBMS must allow users to store
retrieve and update information as easily as possible, without having to be aware
of the internal structure of the database.
2. Creation and maintenance of the data dictionary
3. Managing the facilities for sharing the database. The DBMS has to ensure that
problems do not arise when two people simultaneously access a record and try to
update it
4. Back up and recovery. The DBMS must provide the ability to recover the
database in the event of system failure.
5. Security. The DBMS must handle password allocation and checking, and the
‘view’ of the database that a given user is allowed.
The data dictionary
The data dictionary is a ‘database about the database’. A data dictionary, as defined in
the IBM Dictionary of Computing, is a "centralized repository of information about data
such as meaning, relationships to other data, origin, usage, and format."[1]
The term may
have one of several closely related meanings pertaining to databases and database
management systems (DBMS):
 a document describing a database or collection of databases
 an integral component of a DBMS that is required to determine its structure
 a piece of middleware that extends or supplants the native data dictionary of a
DBMS

It will contain information such as:
1. What tables and columns are included in the present structure?
2. The names of the current tables and columns
3. The characteristics of each item of data, such as its length and data type;
4. Any restrictions on the value of certain columns
5. The meaning of any data fields that are not self-evident; for example, a field such
as ‘course type’;
6. The relationships between items of data
7. Which programs access which items of data, and whether they merely read the
data or change it?
Advantages and any disadvantages of databases
# ADVANTAGES # DISADVANTAGES
1 Supports data sharing 1 Limitations of databases arise from
increased technological complexity
2 Ensures increased data security 2 Developing a large database and installing a
DBMS can be difficult and expensive.
3 Ensures data independence 3 More hardware capability is required, since
storage requirements for the organization of
data, overhead control data, and the DBMS
is greater
4 Data integrity is guaranteed. The functions
in the DBMS can be used to enforce the
integrity rules with minimum programming
in the application programs.
4 Problems of data inconsistency can arise if
a distributed database approach is used.
5 Reduces or minimizes data redundancy 5 Longer processing times may result from
high volume transaction processing
applications since extra layer software [the
DBMS] exists between application
programs and the Operating system.
6 Consistence of data is ensured 6 Security and integrity of data are major
concerns.
7 Support data integration. Since related
data is stored in one single database,
enforcing data integrity is much easier
Centralized databases are vulnerable to
errors, fraud and failures.
8 Related data can be shared across
programs since the data is stored in a
centralized manner
9 Enforcing of standards in the organization
and structure of data files is required and
also easy in a Database System, since it is
one single set of programs, which is always
interacting with data files
10 The application programmer need not build
the functions for handling issues like
concurrent access, security, data integrity,
etc. The programmer only needs to
implement the application business rules.
This brings in application development
ease.

Q* Limitations of file Processing Systems that the DBM system address
i. Data duplication - Same kind of information is stored in several files
ii. Lack of Data integration – Independent files make it difficult to provide end users with
info for ad-hoc requests that require accessing data stored in different files
iii. Data dependence – In a file processing system, the organization of files, their physical
location on storage hardware and application software used to access those files depend
on each other.
Changes in format and structure o data and records in file require changes to all the
programs
Q* what is a DBMS (Data base Management System)
Is a collection of software programs that:
i. Stores data , in a uniform and consistent way
ii. Organizes the data, into records in a uniform and consistent way
iii. Allows access to the data, in a uniform and consistent way
 A collection of software programs that stores organizes and allows access to the
data in a uniform and consistent way
 Is a collection of programs that enables users to create and maintain a database?
 A general purpose software system that facilitates the process of defining
constructing and manipulating databases for various applications.
Database Environment
i. Database
ii. Database users
iii. DBM System
iv. Data Dictionary
v. Database Administrator
vi. User/system interface
Database Users
i. Casual users
ii. Naïve users – parametric users
iii. Sophisticated end users
I. Occasionally use it, and if they do a HLL such as AQL may be used.
II. Those who use Standard queries and updates only e.g. bank cashiers, data entry
clerks’ e.t.c.
III. Know the whole range of facilities on a database environment.
Q a. Explain the 3 Major disadvantages of a file system (6)
b. Give and explain any 7 functions of a DBMSystem
FUNCTIONS OF A Database Management SYSTEM
1. Storage, Retrieval &Update
2. Catalogue
3. Logical transactions
4. Concurrency control
5. Recovery
6. Security
7. Communications

8. Integrity
9. Data Independence
10. Utilities
1. Storage, Retrieval &Update
- Allows users with the ability to store, retrieve and update data in the database.
2. Catalogue
- Allows a catalogue in which descriptions of data items are stored and which is
accessible to users
3. Logical Transactions
- Allows a mechanism which will ensure that either all of the updates
corresponding to a given transaction are made or not made. .e.g.
ABORT – ROLLBACK or undo all the changes
COMMIT- Transaction gone thru and is already in the database.
4. Concurrency Control
- Allows a mechanism to ensure that the database is updated correctly when
multiple users are updating the database concurrently
LOCKING OR DEADLOCK situations must be avoided
5. Recovery
- Allows a mechanism for recovering the database in the event that the database is
damaged in any way.
- A before / after image is usually created
6. Security
- Allows a mechanism to ensure that only authorized users can access the database.
- Authorizations, encryption features and limited views can be used as security
provisions
7. Communication
- Must be capable of integrating with communications software on the database
environment on a multi-user environment.
8. Integrity
- Allows a mechanism to ensure that both the data in the database and changes to
the data follow certain rules.
9. Data Independence
- (Has facilities to) support the independence of programs from the actual structure
of the database.
10. Utilities
- Provide a set of utility services e.g. optimized
COMPONENTS OF A DBMS
1. Data dictionary/directory
2. Data language
3. Application development tools
4. Security software
5. Report writers
6. Query language
7. Web server software
8. Teleprocessing monitors
9. Archiving, backup and Recovery systems
1. DATA DICTIONARY/ DIRECTORY

 Contains the names and descriptions of every data element in the
database.
 Also contains descriptions of how data elements relate to one another.
 Ensures that data is stored in a uniform and consistent manner hence
reducing redundancy.
2. DATA LANGUAGES
 Data description language (DDL) describes the characteristics of data elements.
 DDL requires the application program to use standardized commands to retrieve and
process data from a database.
 Data manipulation language (DML) consists of commands such as FIND, GET, INSERT
3. APPLICATION DEVELOPMENT TOOLS
 A program designed to help programmers develop application programs that use the
database e.g. CASE TOOLS
4. SECURITY SOFTWARE
 Provides a variety of tools to shield database from unauthorized access and from viruses
5. REPORT WRITERS
 Allows programmers, mgrs and others to design out put reports.
6. QUERY LANGUAGE
 A set of commands used primarily for accessing data from a database.
 You can ask ad-hoc questions of the database interactively without the aid of
programmers.
 Examples SQL, NLQ, QBE. Structured Query language, Natural language Queries and
Query by Example.
7. WEB SERVER SOFTWARE
 Turns the computer system housing database into a web server and enables users with
web connection to access data from wherever they are located.
 Also convert data into a format that is readable by standard browsers.
8. TELEPROCCESSING MONITORS
 A software package that manages communication between the database and remote
terminals.
9. ARCHIVING, BACK UP AND RECOVERY SYSTEMS
 Provides the database manager with tools to make copies of the database.
 Restart/ Recovery systems are tools used to restart the database and to recover lost data in
the event of a failure.
OBJECTIVES AND BENEFITS OF DATABASE APPROACH
1. Data redundancy is reduced –reduces the duplication of data.
2. Data inconsistence avoided.
3. Sharing of data is promoted –since data is stored in centralized.
4. Standards are enforced, thru the data dictionary /catalogue
5. Base of application development /maintenance is available
6. Uniform security/ privacy /integrity control s are applicable to group of users
7. SECURITY – Passwords, access controls
PRIVACY - Authorized users
INTEGRITY – Accurate data
8. Integration of data is achieved - since data is stored in one db
9. Data independence is achieved/ observed - it is the immunity of applications to changes in
storage structure and access strategy.

10. Data accessibility and responsiveness.
11. Structured Query Language e.g. select name from customer where town = Harare”
RISK TO DATABASE APPROACH
1. New, specialized personal
2. Backup – important DBMS function (Recovery)
3. Shared data – conflict and concurrency control
4. Technological complexity
5. Expensive to develop a large database and installing a DBMS can be difficult.
6. More hardware capability is required – storage requirements overhead control data and the DBMS
required more memory
7. Problems of inconsistence can arise if a distributed data approach is used.
8. Longer processing time may result from high volume transaction processing applications.
9. Security and integrity are major concerns.
10. Centralized database are vulnerable to errors fraud and failures.
DATABASE MODELS OR TYPES OF DATABASES
i) Hierarchical database model
ii) Network database model
iii) Relational database model
iv) Object-oriented database model
Hierarchical Database Model
 It resembles an inverted tree structure, organogram or family tree. It reflects one-to-one
(1:1) or one-to-many (1:M) relationships only among the records.
 The uppermost record is called the root and from there data are organized into groups
containing parent and child records(nodes)
 A parent record is allowed to have one or more child records but a child node can have
only one parent
 Because relationships between data items follow clearly defined paths, access to data is
fast
 There is no relationship between brother or sister nodes
 Each record is related to others in a parent-child relationship or tree structure.
 Relationships between among records form a hierarchy or tree structure.
 The relationship among records is one to many since each data element is related only to
one element above it.
 Searching a record involves moving progressively downward from a root and along the
branches of the tree until the desired record is located.
 Hierarchical database management systems operates on the parent child tree-like model.
 These normally have a 1:N relationship and are good for storing data with items
describing attributes, features and so on.
 These could store a book with information on chapters and verses.
 They can also be used to store a database of songs, recipes, models of phones and
anything that can be stored in a nested format.
 One such example of a Hierarchical database management system is a XML document.
Diagram

Network Database Model
 Is almost similar to the hierarchical model but is more flexible and versatile because a
record can be linked to any other record in the model; i.e. the network model can reflect a
many-to-many (M:N) relationship.
 The route to data is not necessarily downwards but can in any direction
 The major advantage is its ability to handle sophisticated relationships among various
records and more than one path can lead to desired data level
 Network complexity limits users in their ability to access the database without the help of
programming staff
 A record can belong to a number of parents
 Relationship among records is many to many
 Allows entry into a database at multiple points because any data element or record can be
related to many other data elements.
 Permits a record to be a member of more than one set at a time Hierarchical and
network models are less flexible than other database models because the relationship
between records must be determined and implemented before a search can be conducted.
 A Network database management system uses a data model similar to Hierarchical
database management systems.
 The major difference here is that the tree structure in the Network models can have a
many parent to many child relational model.
 The Network model structure is based on records and sets and most of these databases
use SQL for manipulation of their data.
 Network database management systems tend to be very flexible but are rarely used and
were very quiet common in the1960s and 1970s.
Diagram

Relational Database Model
 Data elements are viewed as being stored in the form of tables(relations)
 There are no pointers or links to talk about but the data is organized into two
dimensional tables which are known as relations
 Each table is composed of unique rows or records which are also known as tuples
and each cell in the relation must be single valued
 Relationships are either 1:1 or 1:M and in the case where M:N relationships exist
junction tables are created All data elements within the database are viewed as
being stored in the form of tables
 Database Packages based on this structure link records in different or various
tables to provide information to users as long as the share common data elements.
 Data is organized in 2-dimensional tables.
 Relational DBMS are the most widely used database management systems today.
They are relatively easy to use.
 The relational model relies on normalizing data within rows and columns in
tables.
 The data can be related to other data in the same table or other tables which has to
be correctly managed by joining one or more tables.
 Data in this type of model is stored is fixed predefined structures and are usually
manipulated using Structured Query Language (SQL).
 Relational database management systems include Oracle, SQL Server, IBM DB2,
MySQL & others.
Diagram

Object Oriented Model
 Each object is bound together with its own data and a set of instructions that
describe the behaviour and attributes of the object
 The objects use messages to interact with one another e.g. the object building in a
database can have the attributes: type, size, colour etc
 This model uses objects and messages to accommodate new types of data and
provide for advanced data handling
 Each object in an object-oriented database model is bound together with its own
data and a set of instructions that describe the behavior and attributes of the
objects.
 Objects use messages to interact with one another.
 Every object is described by a set of attributes.
 E.g. the object building in a database or architectural drawing may have the
attributes TYPE, SIZE, COLOUR just as in any.
 Every object must have a set of procedures or routines or a set of methods.
 E.G methods for an architectural drawing might include instructions to display,
rotate, or explode the drawing on a screen.
 Object-oriented DBMS borrow from the model of the Object-oriented
programming paradigm. In this database model, the Object and its data or
attributes are seen as one and accessed through pointers rather than stored in
relational table models.
 Object-oriented database models consist of diverse structures and is quite
extensible. This data model was designed to work closely with programs built
with Object-oriented programming languages thereby almost making the data and
the program operate as one.
 There is little commercial implementation of this database model as it is still
developing.
 Examples of Object-oriented DBMS include; IBM DB4 and DTS/S1.

Diagram

DATA SECURITY, COPYRIGHT
AND LEGAL ISSUES
 Data Security/Protection
 Refers to keeping data safe from various hazards or dangers like natural
hazards, deliberate corruption or destruction of software & hardware by
malicious or terrorist acts, illegal access to data by hackers [people who break
into the system] & accidental destruction of data by hardware or software
failure [operator error].
MEASURES TO ENSURE DATA SECURITY
1. Data Encryption/Decryption- Data is coded before transmission over a WAN &
decrypted only if you have the key & code to decrypt the data on the receiving end.
The process of transforming a message in ordinary language i.e. plain text to produce
what is called cipher text which is then send along a communication line/link. The
receiving computer uses another transformation to decode the message.
Decryption
 The process of converting encrypted content back into its original form, often the
process of converting cipher text to plaintext. Decryption is the opposite of
encryption.
Encryption
 Any procedure used in cryptography to convert plaintext into cipher text in order
to prevent anyone except the intended recipient from reading that data. There are
many types of data encryption, and they are the basis of network security.
Common types include Data Encryption Standard and public-key encryption.
Cipher text
 Data that has been transformed by encryption so that its semantic information
content (ie, its meaning) is no longer intelligible or directly available.
2. Firewall
 A firewall is a software program designed to prevent unauthorized access to a PC
or network through a connection to the Internet. It works by monitoring all data
sent to and from the PC and comparing the data with a set of user-defined security
criteria. Any data that does not meet that criteria is blocked. Firewalls also
process encrypted data. They verify the validity of the user. User would require
access to the firewall before they can transmit data. Latest firewalls also have the

ability to detect virus software in packets of data that is sent through the network.
Firewalls disallow data transmission if it detects strains of virus on the data being
transmitted.
3) Usernames & Passwords
 Passwords restrict only authorized personnel/users to have access to the data or
computer rooms [cards]. Passwords bring in an aspect of accountability, if a file is
deleted, the person with the password will be reported as the culprit through
logging. Passwords can be forgotten. Widely used by companies to protect their
equipment & data
4) Authorized entry to computer installations
 Most installations have card readers, voice recognition systems or keypads on the
doors that prohibit entry to unauthorized personnel.
5) Backing-up files on external disks periodically.
6) Keeping backup copies of files in a different location and making about 3 generations
of backup.
7) Saving work frequently
8) Avoiding viruses.
9) Restricting access to the computer room. Access could be only through codes, voice
recognition etc.
10) Installing fire alarms.
11) Lining computer rooms with fire resistant material.
12) Placing the computer room in upper floors of a building to avoid burglaries.
13) Having a security guard 24 hours a day.
Summary - Keeping data secure
Measures that can be taken to keep data safe include:
 Making regular back-ups of files. (Back up copies should be stored safely in
fireproof safes or in another building.)
 Protecting yourself against viruses by running anti-virus software.
 Using a system of passwords so that access to data is restricted.
 Safe storage of important files stored on removable disks - eg locked away in a
fireproof and waterproof safe.
 Allowing only authorized staff into certain computer areas, eg by controlling
entry to these areas by means of ID cards or magnetic swipe cards.
 Always logging off or turning terminals off and if possible locking them.
 Avoiding accidentally deletion of files by write-protecting disks.
 Using data encryption techniques to code data so that it makes no apparent sense
 BACK UP
 Copying or saving data to a different location. One can restore the backup
copy if data is lost or damaged.

 To create a copy of a disk’s contents on another location for safe keeping.
Since hard drives are not infallible, it is recommended that you backup its
contents regularly.
DISASTER PLANNING
 Many companies have comprehensive emergency plans so that even after suffering a
severe:
 Bomb
 Fire damage
 Natural disaster, the company can be up and running within a day or
two.
 A disaster recovery service/programme provides for example
 Office space
 Computer facilities
 Phones
 Desks, at an emergency BACKUP site.
 A completely up to date copy of the company Database may be permanently
maintained at this site with all transactions being transmitted to this remote site
updating the database, copying etc.
 The data should be backed up/stored to one or more media to ensure recovery in
case of disaster.
 The back up procedures and media should be tested periodically to assess their
effectiveness.
Disaster plan
 The documented policies and procedures intended to either prevent damage,
minimize damage, or recover from damage to record materials.
Disaster recovery plan
 The document that defines the resources, actions, tasks and data required to
manage the business recovery process in the event of a business interruption. The
plan is designed to assist in restoring the business process within the stated
disaster recovery goals.
 Part of an overall contingency plan. The plan for a process whereby an enterprise
would restore any loss of data in the event of fire, vandalism, natural disaster, or
system failure.
MAJOR THREATS TO INFORMATION SYSTEMS/COMPUTERS
Key threats to data security
 Data can be lost or damaged during a system crash - especially one affecting the
hard disk.
 Data can become corrupt as a result of faulty disks or disk drives, or power
failures.
 Data can be lost by accidentally deleting or overwriting files.

 Data can be lost or become corrupted by computer viruses.
 Data can be hacked into by unauthorized users and deleted or altered.
 Data can be destroyed by terrorist activities, war, bombs and fire.
 Data can be deleted or altered by unpleasant employees wishing to make money
or seek revenge on their employers.
Explain 5 major threats to information systems; for each threat describe its impact
and preventative measure you would adopt to prevent it. [15].
THREAT IMPACT CONTROL
Hardware
failure
 You are grounded
 You cannot access the system
 Data is incorrectly/
incompletely processed
 Have spares in the warehouse.
 Do regular servicing
 Have a disaster plan
 Run hardware diagnostics frequently
Electrical faults  Loss of data
 Disk crushes
 Damage to hardware
 Have standby generators
 Install UPS [uninterrupted power supply]
 Install Surge suppressors/ protectors
Software
failures
 Operations are grounded  Buy software from reputable vendors.
 Do regular back ups
 Software diagnostics
Natural
disasters/
physical threats
 Absolute destruction  Relocate backups to other areas free from
disasters
Viruses  Deletion & corruption of files
 Reformatting of documents
 System may fail to work
 Install a reliable anti-virus software
 Never download unknown e-mail
attachments
 Scan unknown diskettes
Hackers,
Computer
crime
 Security is breached
 Security is bypassed
 Destruction of files
 Data is stolen
 Change passwords regularly
 Employ a security guard
 Install a firewall
 Prevent unauthorized access to computer
facilities.
War and Terrorist activity
Human error
As use of internet and related telecommunications technologies and systems has become
pervasive ,use of these networks now creates a new vulnerability for organizations or
companies .These networks can be infiltrated or subverted a number of ways .As a result
,organizations or companies will faced threats that affect and vulnerable to information
system security . Threats to information system can come from a variety of places inside
and external to an organizations or companies .In order to secure system and information
,each company or organization should analyze the types of threats that will be faced and
how the threats affect information system security .Examples of threats such as

unauthorized access (hacker and cracker ) ,computer viruses ,theft ,sabotage ,vandalism
and accidents
The Threats of Information System Security

Unauthorized
Access
(Hacker and
Cracker)
One of the most common security risks in relation to computerized
information systems is the danger of unauthorized access to confidential
data .The main concern comes from unwanted intruders, or hackers, who
use the latest technology and their skills to break into supposedly secure
computers or to disable them .A person who gains access to information
system for malicious reason is often termed of cracker rather than a
hacker.
 Spoofing and Sniffing
 Denial of Service Attacks
(DOS)
Computer
Viruses
Computer virus is a kind of nasty software written deliberately to enter a
computer without the user’s permission or knowledge ,with an ability to
duplicate itself ,thus continuing to spread .Some viruses do little but
duplicate others can cause severe harm or adversely affect program and
performance of the system .Virus program may still cause crashes and
data loss .In many cases ,the damages caused by computer virus might be
accidental ,arising merely as the result of poor programming .Type of
viruses ,for example ,worms and Trojan horses .
 Worms
 Trojan horses
Theft The loss of important hardware, software or data can have significant
effects on an organization’s effectiveness .Theft can be divided into three
basic categories: physical theft, data theft, and identity theft.
 Physical Theft
 Data Theft
 Identity Theft
Sabotage With regard to information systems , damage may be on purpose or
accidental and carried out an individual basis or as an act of industrial
sabotage .Insiders have knowledge that provide them with capability to
cause maximum interruption to an agency by sabotaging information
systems .Examples include destroying hardware and infrastructure
,changing data ,entering incorrect data ,deleting software ,planting logic
bombs ,deleting data ,planting a virus .
 Individual Sabotage
 Industrial Sabotage
 Unintentional Sabotage
Vandalism Deliberate damage cause to hardware, software and data is considered a
serious threat to information system security .The threat from vandalism
lies in the fact that the organization is temporarily denied access to
someone of its resources .Even relatively minor damage to parts of a
system can have a significant effect on the organization as a whole.
Accidents Major of damage caused to information systems or corporate data arises
as a result of human error .Accidental misuse or damage will be affected
over time by the attitude and disposition of the staff in addition to the
environment .Human errors have a greater impact on information system
security than do manmade threats caused by purposeful attacks .But most
accidents that are serious threats to the security of information systems
can be mitigated.
 Inaccurate data entry
 Attempts to carry out
tasks beyond the ability of
the employee
The 10 most common security threats
THREAT
1. Malware: Malware is short for “malicious software.” Wikipedia describes malware as a term used to mean a “variety of forms of
hostile, intrusive, or annoying software or program code.” Malware could be computer viruses, worms, Trojan horses,
dishonest spyware, and malicious rootkits—all of which are defined below.

2. Computer
virus:
A computer virus is a small piece of software that can spread from one infected computer to another. The virus could
corrupt, steal, or delete data on your computer—even erasing everything on your hard drive. A virus could also use other
programs like your email program to spread itself to other computers.
3. Rogue
security
software:
Have you ever seen a pop-up window that advertises a security update or alert? It appears legitimate and asks you to click
on a link to install the “update” or “remove” unwanted malicious software that it has apparently detected. This could be
rogue security software designed to lure people into clicking and downloading malicious software. Microsoft has a useful
webpage that describes rogue security software and how you can protect yourself.
4. Trojan
horse:
Users can infect their computers with Trojan horse software simply by downloading an application they thought was
legitimate but was in fact malicious. Once inside your computer, a Trojan horse can do anything from record your
passwords by logging keystrokes (known as a keystroke logger) to hijacking your webcam to watch and record your
every move.
Trojan horses, commonly referred to as Trojan, are programs. They masquerade as normal, safe applications, but their
mission is to allow a hacker remote access to your computer. In turn, the infected computer can be used as part of a
denial of service attack and data theft can occur.
A particularly nasty Trojan is a keystroke logger than can be used to capture passwords, credit card numbers and other
sensitive information.
5. Malicious
spyware:
Malicious spyware is used to describe the Trojan application that was created by cybercriminals to spy on their victims.
An example would be keylogger software that records a victim’s every keystroke on his or her keyboard. The recorded
information is periodically sent back to the originating cybercriminal over the Internet. Keylogging software is widely
available and is marketed to parents or businesses that want to monitor their kids’ or employees’ Internet usage.
Spyware usually invades computers through software downloads. Shareware and freeware downloads, in addition to
peer-to-peer file sharing are typical infection points. Like Trojans, spyware can pilfer sensitive information, but are often
used as advertising tools as well. The intent is to gather a user's information by monitoring Internet activity and
transmitting that to an attacker.
6. Computer
worm:
A computer worm is a software program that can copy itself from one computer to another, without human interaction.
Worms can replicate in great volume and with great speed. A worm is a specific type of virus. Unlike a typical virus, it's
goal isn't to alter system files, but to replicate so many times that it consumes hard disk space or memory. Worm victims
will notice their computers running slower or crashing.
7. Botnet: A botnet is a group of computers connected to the Internet that have been compromised by a hacker using a computer
virus or Trojan horse. An individual computer in the group is known as a “zombie“computer.
The botnet is under the command of a “bot herder” or a “bot master,” usually to perform nefarious activities. This could
include distributing spam to the email contact addresses on each zombie computer, for example. If the botnet is
sufficiently big in number, it could be used to access a targeted website simultaneously in what’s known as a denial-of-
service (DoS) attack. The goal of a DoS attack is to bring down a web server by overloading it with access requests.
Popular websites such as Google and Twitter have been victims of DoS attacks.
8. Spam: Spam in the security context is primarily used to describe email spam —unwanted messages in your email inbox. Spam,
or electronic junk mail, is a nuisance as it can clutter your mailbox as well as potentially take up space on your mail
server. Unwanted junk mail advertising items you don’t care for is harmless, relatively speaking. However, spam
messages can contain links that when clicked on could go to a website that installs malicious software onto your
computer.
9. Phishing: Phishing scams are fraudulent attempts by cybercriminals to obtain private information. Phishing scams often appear in
the guise of email messages designed to appear as though they are from legitimate sources. For example, the message
would try to lure you into giving your personal information by pretending that your bank or email service provider is
updating its website and that you must click on the link in the email to verify your account information and password
details.
10. Rootkit: According to TechTarget, a rootkit is a collection of tools that are used to obtain administrator-level access to a computer
or a network of computers. A rootkit could be installed on your computer by a cybercriminal exploiting a vulnerability or
security hole in a legitimate application on your PC and may contain spyware that monitors and records keystrokes.
Rootkits are some of the most difficult to detect. They are activated when your system boots up -- before anti-virus
software is started. Rootkits allow the installation of files and accounts, or the purposes of intercepting sensitive
information.
Definitions of computer abuse on the Web:
 The willful or negligent unauthorized activity that affects the availability,
confidentiality, or integrity of computer resources. Computer abuse includes

fraud, embezzlement, theft, malicious damage, unauthorized use, denial of
service, and misappropriation

Definitions of hacking on the Web:
 Unauthorized use, or attempts to circumvent or bypass the security mechanisms of
an information system or network. Hacking means illegally accessing other
people's computer systems for destroying, disrupting or carrying out illegal
activities on the network or computer systems.
DATA INTEGRITY/RELIABILITY
 Refers to the correctness AND The accuracy of data after being transmitted or
processed
 Data in the computer system may become incorrect, corrupted or of poor quality
in many different ways & at any stage during data processing.
 Consequences of system failure:
 Loss of business due downtime
 Delays
 Air traffic control system could well have catastrophic results
COMPUTER CRIME/FRAUD
 Computer crimes are criminal activities, which involve the use of information
technology to gain an illegal or an unauthorized access to a computer system with
intent of damaging, deleting or altering computer data. Computer crimes also
include the activities such as electronic frauds, misuse of devices, identity theft
and data as well as system interference. Computer crimes may not necessarily
involve damage to physical property. They rather include the manipulation of
confidential data and critical information. Computer crimes involve activities of
software theft, wherein the privacy of the users is hampered. These criminal
activities involve the breach of human and information privacy, as also the theft
and illegal alteration of system critical information. The different types of
computer crimes have necessitated the introduction and use of newer and more
effective security measures.
 Computer Fraud/Crime
 Criminal actions accomplished through the use of computer systems,
especially with the intent to defraud, destroy, damage, or make
unauthorized use of computer resources.

 E.g. improper transfer of funds from one account to another
TYPES OF COMPUTER CRIME/FRAUD
a) Intellectual Crime – cracking into a computer system for the purpose of transferring
or obtaining funds is a typical e.g.
b) Destruction of property – destroying a computer property
c) Theft – Software piracy which is unauthorized copying of software. Hardware &
software being taken away without the knowledge/consent of its owners.
d) Fraud achieved by the manipulation of computer records.
e) * Spamming wherever outlawed completely or where regulations controlling it are
violated.
f) * Deliberate circumvention of computersecurity systems.
g) * Unauthorized access to or modification of programs (see software cracking and
hacking) & data.
h) * Intellectual property theft, including software piracy.
i) * Industrial espionage by means of access to or theft of computer materials.
j) * Identity theft where this is accomplished by use of fraudulent computer
transactions.
k) * Writing or spreading computerviruses or worms.
l) * Salami slicing is the practice of stealing money repeatedly in extremely small
quantities.
m) *DNSDenial-of-service attack, where company websites are flooded with service
requests and their website is overloaded and either slowed or crashes completely.
n) * Making and digitally distributing child pornography
Types of Computer Crime
Hacking: The activity of breaking into a computer system to gain an unauthorized access
is known as hacking. The act of defeating the security capabilities of a computer system
in order to obtain an illegal access to the information stored on the computer system is
called hacking. The unauthorized revelation of passwords with intent to gain an
unauthorized access to the private communication of an organization of a user is one of
the widely known computer crimes. Another highly dangerous computer crime is the
hacking of IP addresses in order to transact with a false identity, thus remaining
anonymous while carrying out the criminal activities.
Phishing: Phishing is the act of attempting to acquire sensitive information like
usernames, passwords and credit card details by disguising as a trustworthy source.
Phishing is carried out through emails or by luring the users to enter personal information
through fake websites. Criminals often use websites that have a look and feel of some
popular website, which makes the users feel safe to enter their details there.
Computer Viruses: Computer viruses are computer programs that can replicate
themselves and harm the computer systems on a network without the knowledge of the
system users. Viruses spread to other computers through network file system, through the
network, Internet or by the means of removable devices like USB drives and CDs.

Computer viruses are after all, forms of malicious codes written with an aim to harm a
computer system and destroy information. Writing computer viruses is a criminal activity
as virus infections can crash computer systems, thereby destroying great amounts of
critical data.
Cyberstalking: The use of communication technology, mainly the Internet, to torture
other individuals is known as cyberstalking. False accusations, transmission of threats
and damage to data and equipment fall under the class of cyberstalking activities.
Cyberstalkers often target the users by means of chat rooms, online forums and social
networking websites to gather user information and harass the users on the basis of the
information gathered. Obscene emails, abusive phone calls and other such serious effects
of cyberstalking have made it a type of computer crime.
Identity Theft: This is one of the most serious frauds as it involves stealing money and
obtaining other benefits through the use of a false identity. It is the act of pretending to be
someone else by using someone else's identity as one's own. Financial identity theft
involves the use of a false identity to obtain goods and services and a commercial identity
theft is the using of someone else’s business name or credit card details for commercial
purposes. Identity cloning is the use of another user's information to pose as a false user.
Illegal migration, terrorism and blackmail are often made possible by means of identity
theft.
The different types of computer crimes involve an illegal exploitation of the computer
and communication technology for criminal activities. While the advancing technology
has served as a boon to mankind, the destructively directed human intellects are all set to
turn technology into a curse. However, crimes are sure to end, as it is truth that always
triumphs!
1. Intellectual crime – cracking into a computer system with the sole aim of
transferring or stealing funds, e.g. Salami slicing which is the activity of
obtaining or stealing money repeatedly in extremely small quantities over a period
of time
2. Destruction of property
3. Software piracy
4. Deliberate circumvention of computer security systems or unauthorized access to
or modification of computer programs and data; i.e. hacking which attempts to
bypass the security mechanism of a computer system or network
5. Theft of computer hardware and software or taking away software without the
owner’s consent
6. Making and distributing pornography
MEASURES TO COUNTER OR COMBAT COMPUTER CRIME [COMPUTER
SECURITY]
 Careful vetting of employees

 Separation of duties
 Use of passwords
 Security manager software-to monitor attempts to access the system
whether successful or not.
 Educating staff
 Prevention of unauthorized access to the computer operations room
 Data Encryption/Decryption
1. Establish strong passwords
Implementing strong passwords is the easiest thing you can do to strengthen your
security.
Cloutier shares his tip for crafting a hard-to-crack password: use a combination of
capital and lower-case letters, numbers and symbols and make it 8 to 12
characters long.
You should definitely avoid using: any personal data (such as your
birthdate), common words spelled backwards and sequences of characters or
numbers, or those that are close together on the keyboard.
Use their convenient password checker to see how strong yours is.
As for how often you should change your password, Cloutier says that the
industry standard is "every 90 days," but don't hesitate to do it more frequently if
your data is highly-sensitive.
Another key: make sure every individual has their own username and password
for any login system, from desktops to your CMS. "Never just use one shared
password," says Cloutier.
And finally, "Never write it down!" he adds.
2. Put up a strong firewall
In order to have a properly protected network, "firewalls are a must," Cloutier
says.
A firewall protects your network by controlling internet traffic coming into and
flowing out of your business. They're pretty standard across the board -- Cloutier
recommends any of the major brands.
3. Install antivirus protection
Antivirus and anti-malware software are essentials in your arsenal of online
security weapons, as well.
"They're the last line of defense" should an unwanted attack get through to your
network, Cloutier explains.
4. Update your programs regularly
Making sure your computer is "properly patched and updated" is a necessary step

towards being fully protected; there's little point in installing all this great
software if you're not going to maintain it right.
"Your security applications are only as good as their most recent update,"
Watchinski explains. "While applications are not 100 percent fool-proof, it is
important to regularly update these tools to help keep your users safe."
Frequently updating your programs keeps you up-to-date on any recent issues or
holes that programmers have fixed.
5. Secure your laptops
Because of their portable nature, laptops are at a higher risk of being lost or stolen
than average company desktops. It's important to take some extra steps to make
certain your sensitive data is protected.
Encryption software changes the way information looks on the harddrive so that,
without the correct password, it can't be read.
6. Secure your mobile phones
Cloutier points out that smartphones hold so much data these days that you should
consider them almost as valuable as company computers -- and they're much
more easily lost or stolen. As such, securing them is another must.
The must-haves for mobile phones:
 Encryption software
 Password-protection (Cloutier also suggests enabling a specific "lock-out"
period, wherein after a short amount of time not being used, the phone locks
itself)
 Remote wiping enabled
7. Backup regularly
Scheduling regular backups to an external hard drive, or in the cloud, is a painless
way to ensure that all your data is stored safely.
The general rule of thumb for backups: servers should have a complete backup
weekly, and incremental backups every night; personal computers should also be
backed up completely every week, but you can do incremental backups every few
days if you like ("however long you could live without your data," Cloutier
explains).
Getting your data compromised is a painful experience -- having it all backed up
so you don't completely lose it will make it much less so.
8. Be careful with e-mail, IM and surfing the Web
It's not uncommon for a unsuspecting employee to click on a link or download an
attachment that they believe is harmless -- only to discover they've been infected
with a nasty virus, or worse.
9. Educate your employees
Teaching your employees about safe online habits and proactive defense is
crucial.
"Educating them about what they are doing and why it is dangerous is a more
effective strategy than expecting your IT security staff to constantly react to end
users’ bad decisions," Watchinski says.
It's not easy: "One of the most difficult things to do is protect end users against
themselves," he adds. But ultimately, prevention is the best approach to handling
your data security.

Make sure your employees understand how important your company's data is, and
all the measures they can take to protect it.
10. Data encryption
Encryption scrambles data, and is used to protect information that is being held on
a computer, stored on external media such as DVDs or transmitted over a
network.
11. Intrusion detection
These products monitor system and network activity to spot potential security
breaches. If a detection system suspects an attack, it can generate an alarm, such
as an email alert, based upon the type of activity it has identified.
COMPUTER VIRUS
What is it?
 An executable computer program written intentionally to alter the way a
computer operates without permission, to do harm to the computer.
Types of Computer Viruses
 Macro Viruses – are programmed as macros and embedded into a file or
document and when the document is opened the virus is activated. A macro is a
list of commands or actions that are found under key names of headings. Macro
viruses typically infect global settings files such as Word templates so that
subsequently edited documents are contaminated with the infective macros
 Boot Sector Viruses – A virus which attaches itself to the first part of the hard
disk that is read by the computer upon bootup. These are normally spread by
floppy disks. They only affect the computer’s boot sector such that the next time
you try to start the computer it fails to boot
 Time Bomb – is designed to cause damage to a computer at a specified date and
time, e.g. Friday 13th
, March 6th
 Logic Bomb – checks for particular conditions or states of the system which
when satisfied triggers the perpetration of an unauthorized and usually destructive
act. It lies dormant for most of the time and is triggered by an event
 Memory resident virus – resides in a computer’s volatile memory (RAM).
 Polymorphic viruses – a virus that not only replicates itself by creating multiple
files of itself, but it also its digital signature every time it replicates. This makes it
difficult for less sophisticated antivirus software to detect
 Program viruses e.g. cascade, pacman 1508, override.
 Boot viruses e.g. pasta, pentagon, Michelangelo
 Internet Viruses e.g. Trojan horse, Stealth
DEFINITION2.

A virus is a computer program designed to enter your computer and tamper with your
files without your knowledge. Once the program containing the virus is open, the
activated virus can not only infect other programs and documents on your computer, it
can duplicate and transmit itself to other computers that are connected to yours, just like
a physical virus can move from one human host to another.
Virusesbegan in the late 1980s as personal computers and electronic bulletin boards
became more common. Back then, operating systems, word processing programs and
other programs were stored on floppy disks. Hidden Viruseswere programmed onto these
disks; as the disks were transferred from person to person, the virus spread.
WHO CREATES VIRUSES?
Where do Virusescome from? Every virus is created by an author with a different
motive—but all virus builders feel their actions are justified. For some, a killer virus is
the ultimate technical challenge, like climbing a mountain. For others, creating Viruses is
a form of self-expression. Some disgruntled employees, consumers or citizens turn to
virus building as revenge for perceived injustices. And though it’s a frightening thought,
some Virusesare built and aimed by legitimate (but disreputable) businesses to weaken
competitors. Other virus authors want to make their mark in Internet history; these writers
get a thrill out of seeing their virus cause damage enough to attract news headlines both
online and on the evening news.
What Viruses Do? /Signs & symptoms of an infected computer.
 Reduced memory or disk space
 Files are overwritten or damaged
 Hard drive may be erased
 Data is modified /corrupted.
 Change files & date stamp
 Drive lights blink without reason
 Longer times are experienced when loading programs
 Slower system operation.
 Deletion of data files
 The computer completely fails to work
 Erasure or deletion of executable files
 Formatting of the hard disks
 Filling up of disk space
 Programs suddenly take longer to load.
 The size of a program changes.
 The disk runs out of free space when it seems to have plenty.
 The CHKDSK command does not show the correct amount of bytes available.
 Bit errors frequently occur while running Windows.
 The disk drive is active when it should not be.
 The hard drive is inaccessible when booting from a floppy drive.
 Unrecognized files appear.

 File names change.
 The keyboard makes a clicking noise.
 The screen becomes distorted.
 Text on screen does unusual things.
 CMOS settings, AUTOEXEC.BAT, or CONFIG.SYS files change unexpectedly
(Symantec).
A large part of detection is anti-virus software. Like a doctor, anti-virus
software often uses the above listed symptoms to identify and eradicate an
infection.
What are the symptoms of an infected computer?
It’s not always easy to tell if your computer has been compromised. More than ever
before, the authors of viruses, worms, Trojans and spyware are going to great lengths to
hide their code and conceal what their programs are doing on an infected computer.
That’s why it’s essential to follow the advice given in this guide: in particular, install
Internet security software, make sure you apply security patches to your operating system
and applications and backup your data regularly.
It’s very difficult to provide a list of characteristic symptoms of a compromised computer
because the same symptoms can also be caused by hardware and/or software problems.
Here are just a few examples:
 Your computer behaves strangely, i.e. in a way that you haven’t seen before.
 You see unexpected messages or images.
 You hear unexpected sounds, played at random.
 Programs start unexpectedly.
 Your personal firewall tells you that an application has tried to connect to the
Internet (and it’s not a program that you ran).
 Your friends tell you that they have received e-mail messages from your address
and you haven’t sent them anything.
 Your computer ‘freezes’ frequently, or programs start running slowly.
 You get lots of system error messages.
 The operating system will not load when you start your computer.
 You notice that files or folders have been deleted or changed.
 You notice hard disk access (shown by one of the small flashing lights) when
you’re not aware of any programs running.
 Your web browser behaves erratically, e.g. you can’t close a browser window.
How computers are infected with Viruses?
 Use of infected floppy diskettes on uninfected computers. Floppy disks or
other media that users can exchange.
 Downloading unknown files, when your computer is connected to the Internet.
 Opening an E-mail attachment. Email attachments.
 Accepting unknown program installations from the internet

 Use of network files/direct connection/through networks.
 Software piracy [buying software from unauthorized agents]. Pirated software.
 Booting a PC from an infected medium.
 Executing an infected program.
 Opening an infected file.
 Shareware.
 Viruses may be sent by opening email attachments,
 clicking on spam,
 visiting corrupt websites and links online,
 Opening spreadsheets or even the original method—infected disks.
 But the Internet is now the superhighway for virus transmission.
Sharing of storage media
 Through e-mail attachments
 Networks – if your computer is connected to a home network or if your work
computer is part of network, you may find yourself with an infection through no
fault of your own. There isn’t much you can do to stop these kinds of infections,
short of having your network administrator ensure that everyone’s antivirus
software is up to date so that the invading bug can be removed as quickly as
possible.
 Internet downloads including software piracy
 Rogue Websites. It is depressing to know that you may become infected with
spyware or a virus by doing nothing more than simply visiting a website, but it
istrue. Many adult websites, gambling websites and other less than trustworthy
websites will attempt to automatically access your computer when you visit them.
They often install adware bugs that will cause a flurry of pop ups to appear on
your screen. This adware will often allow for other programs with even more
nefarious purposes to be installed and before you know it, your computer will be
swamped. To stop these rogue websites, adjust the settings on your antivirus
software and firewall so that no outside connections can be made and no
programs can be installed without your express permission.
CHARACTERISTICS and ATTRIBUTES OF COMPUTER VIRUSES
The demonstrated characteristics of computer viruses include several remarkable items,
including size, versatility, propagation, effectiveness, functionality, and persistence.
1) Size.The sizes of the program code required for computer viruses has been
demonstrated to be surprisingly small. This has facilitated the ability of these
programs to attach themselves to other applications and escape notice for long periods
of time.
2) Versatility.computer viruses have appeared with the ability to generically attack a
wide variety of applications. Many do not even require information about the
program they are infecting.

3) Propagation. Once a computer virus has infected a program, while this program is
running, the virus is able to spread to other programs and files accessible to the
computer system. The ability to propagate is essential to a virus program.
4) Effectiveness. Many of thecomputer viruses that have received widespread publicity
have had far-reaching and catastrophic effects on their victims. These have included
total loss of data, programs, and even the operating systems.
5) Functionality. A wide variety of functions has been demonstrated in virus programs.
Some virus programs merely spread themselves to applications without otherwise
attacking data files, program functions, or operating systems activities. Other virus
programs are programmed to damage or delete files and systems. The effectiveness of
these programs is enhanced through the use of several phases of operation, in which
the virus propagates through a system or lies dormant until triggered by a specified
event. This allows the virus program increased time to spread before the victim
system's user becomes aware of its presence.
6) Persistence. Even after the virus program has been detected, recovery of data,
programs, and even system operation has been difficult and time consuming. In many
cases, especially in networked operations, eradication of viruses has been complicated
by the ability of the virus program to repeatedly spread and reoccur through the
networked system from a single infected copy.
Attributes of computer viruses
o Auto replicating [self replicating].
o Attaches itself to a program or file
o It infects as it travels
o Reproduces itself
o Distribute itself
o Copies itself
o Duplicate copies of itself
o It spreads
o It is software
o It can destroy
o It hides
DESTRUCTIVE EFFECTS OF COMPUTER VIRUSES
o Cause damage to data
o Extract data from machines for spying or theft
o Slow machine performance
o Corrupt data
o Damage software, hardware and files
o Damage the computer by damaging programs
o Reformatting of the hard disk
o Deletion of files

Top 15 ANTIVIRUS TOOLS/PACKAGES/SOFTWARE
15. ESET NOD32 Antivirus 8
14. Webroot Internet Security Plus 2015
13. Panda Global Protection 2015
12. G-Data Internet Security 2015
11. McAfee LiveSafe 2015
10. AVG Free Antivirus 2016
9. Avast Free Antivirus 2015
8. Panda Free Antivirus 2016
7. Qihoo 360 Total Security 2016
6. Trend Micro Internet Security 2015
5. BitDefender Antivirus Free Edition 2016
4. Avira Free Antivirus 2015
3. Kaspersky Total Security 2015
2. Bitdefender Internet Security 2015
1. Symantec Norton Security with Backup
SCANNER – examine every file on a specific disk drive, looking/searching for known
virus
“signatures”. A “signature” is a string of software code that identifies a virus program.
Every virus has a unique signature
MEASURES/FACILITIES PROVIDED BY AN ANTIVIRUS PACKAGE.
1. Scanning – searching for viruses
2. Cleaning of the system (removal of viruses)
3. Rearrangement of corrupted data.
4. Repairing of corrupted data files.
5. Quarantine – separation of infected files from uninfected files.
6. Prevention includes creating user awareness, implementing hygiene rules,
using disk authorization software, or providing isolated 'quarantine' PCs.
7. Detection involves the use of anti-virus software to detect, report and
(sometimes) disinfect viruses..
8. Containment involves identifying and isolating the infected items.
9. Recovery involves disinfecting or removing infected items, and recovering or
replacing corrupted data.
PRECAUTIONS/SAFETY GUIDES AGAINST VIRUSES
 Install a reliable antiviral package
 Avoid Software piracy thus buy software from authorized dealers.
 Never download unknown files from the internet

 Boot the system from virus free disks
 Using write protect tabs on floppy disks
 Scan every floppy diskette for viruses before use. Unknown floppy
diskettes should not be used
 Avoid using foreign storage media
 Use genuine software
 Avoid opening e-mails from suspicious or unknown sources
 Write protect disks
 Install antivirus software, e.g. Avira, Eset Nod32, AVG, Norton, Dr.
Solomon’s Toolkit
 Install a reliable anti virus program – From the first moment you turn your computer
on, you should have a trusted anti virus program by your side. Even if you have a
machine that isn’t hooked up to the Internet, a reliable anti virus program is a low cost
and common sense addition to any machine. There are even free anti virus programs you
can download that work almost as well as industry giants like Norton and McAfee.
 Install anti-spyware and anti-malware programs – As good as the best anti virus
programs are, they sometimes need a little bit of help. Thankfully, many of the top anti-
spyware programs are completely free. Spybot Search and Destroy and CCleaner are just
two free programs that can help prevent computer viruses from doing any damage on
your machine. As helpful as these programs are, however, you must update them and run
them on a regular basis for them to do any good.
 Avoid suspicious websites – A good virus protection program will alert you when you
visit a website that attempts to install or run a program on your computer. Many less than
reputable adult websites do this, so if you get a warning, don’t go back, you may end up
with a bug you can’t get rid of.
 Never Open Email Attachments Without Scanning Them First – The most common
way viruses are spread throughout the Internet is still via email. Some attachments, like
pictures, now display in emails and don’t require an attachment to be manually opened,
but other documents do. Make sure you use an email client that scans all email
attachments before you are allowed to open them. This will help prevent computer
viruses from getting a foothold on your machine.
 Set up Automatic Scans – Many of the top anti virus programs, as well as the best anti-
spyware programs, now have settings that will let them automatically run during down
times or in the middle of the night. Of course, your computer must be on for this to
happen, but having daily scans run when nothing else is going on is a great way to
prevent even the latest computer viruses from sticking around too long.
 Watch Your Downloads – Part of the fun of the Internet is downloading music, movies
and other items. However, since these downloads are so massive, it can be easy to sneak
a virus along for the ride. Only download these files from trusted sites that you can count
on, or, at the very least, scan them before you open them.
 Updates, Updates, Updates – There is a reason why Windows has a feature called
Critical Updates. There is an entire branch of Microsoft dedicated to staying one step
ahead of the hackers out there so when they manage to fix a possible security loophole,
you need to download the patch right away. Help Microsoft help you prevent computer
viruses from causing too much trouble.

 Know What To Look For – Even if you are just a casual computer user, you should
have an idea of how your machine operates, what normal pop up windows look like and
what popular viruses are out there, that way, when your computer begins exhibiting tell
tale signs, you’ll know. You can help prevent computer viruses by staying updated and
educated.
 Stay Away From Cracked Software – It is so secret that you can download illegal,
cracked versions of some programs online. As tempting as it may be, these files are
almost always infested with advanced and difficult to detect bugs. Play it safe and get
your software from the source.
 Install a Firewall – A firewall is a program that screens incoming Internet and network
traffic. Along with your virus program, it can help prevent unauthorized access to your
computer.
 Be prepared to Lock Down – If you hear of a virus that is spreading like wildfire
through the Internet, make an extra effort to be careful. Don’t open any suspicious emails
or accept any downloads for a week or two until your virus protection program has been
updated and you are, once again, safe.
FILE MANAGEMENT & FILE CONCEPTS
FILE MANAGEMENT
 File management is the storing, naming, sorting and handling computer files.
 It is the process of maintaining folders, documents and multimedia into categories
and subcategories as desired by a user.
 Fundamental aspects of file management are organizing, labeling and classifying
computer data.
 File management helps to eliminate clutter so that a user can access and retrieve data
faster and more conveniently.

 There are two types of file managers: electronic and three-dimensional.
 Three-dimensional file management is basically the traditional method of keeping
hard-copy documents in cabinets and safes.
 However, digital and electronic technology has evolved and enabled better
management, access and retrieval of documents.
 It enables users to sort files by type, size, name, color and date that they were created
or modified.
 This orderly arrangement saves time usually spent looking for records, which
maximizes productivity.
 Most common operations done on stored computer files are editing, viewing, playing,
copying, moving and deleting.
 Modern applications have been developed to help users search, access and manage
files in a computer and mobile devices.
 Creating master folders for related files helps to organize files more efficiently.
 Documents, music and movies can be the master folders for all other files.
 Next, a user may create several subfolders under the main one to differentiate data
File Management System
 A file management system is a type of software that manages data files in a computer
system.
 It has limited capabilities and is designed to manage individual or group files, such as
special office documents and records.
 It may display report details, like owner, creation date, state of completion and similar
features useful in an office environment.
 A file management system is also known as a file manager.
 A file management system should not be confused with a file system, which manages
all types of data and files in an operating system (OS
The system may contain features like:
 Assigning queued document numbers for processing
 Owner and process mapping to track various stages of processing
 Report generation
 Notes
 Status
 Create, modify, copy, delete and other file operations

File system
 Is the way in which files are named and where they are placed logically for storage and
retrieval?
 Without a file system, stored information wouldn't be isolated into individual files and would
be difficult to identify and retrieve.
 As data capacities increase, the organization and accessibility of individual files are becoming
even more important in data storage.
 Digital file systems and files are named for and modeled after paper-based filing systems
using the same logic-based method of storing and retrieving documents.
 File systems can differ between operating systems (OS), such as Microsoft Windows, macOS
and Linux-based systems.
 Some file systems are designed for specific applications.
 Major types of file systems include distributed file systems, disk-based file systems and
special purpose file systems.
How file systems work
A file system stores and organizes data and can be thought of as a type of index for all the data
contained in a storage device. These devices can include hard drives, optical drives and flash
drives.
File systems specify conventions for naming files, including the maximum number of characters
in a name, which characters can be used and, in some systems, how long the file name suffix can
be. In many file systems, file names are not case sensitive.
Along with the file itself, file systems contain information such as the size of the file, as well as
its attributes, location and hierarchy in the directory in the metadata. Metadata can also identify
free blocks of available storage on the drive and how much space is available.
Example of a file tree diagram
A file system also includes a format to specify the path to a file through the structure of
directories. A file is placed in a directory -- or a folder in Windows OS -- or subdirectory at the
desired place in the tree structure. PC and mobile OSes have file systems in which files are placed
somewhere in a hierarchical tree structure.

Before files and directories are created on the storage medium, partitions should be put into place.
A partition is a region of the hard disk or other storage that the OS manages separately. One file
system is contained in the primary partition, and some OSes allow for multiple partitions on one
disk. In this situation, if one file system gets corrupted, the data in a different partition will be
safe.
File systems and the role of metadata
File systems use metadata to store and retrieve files. Examples of metadata tags include:
 Date created
 Date modified
 Last date of access
 Last backup
 User ID of the file creator
 Access permissions
 File size
File Management Commands
USE A DESKTOP OR LAPTOP TO PRACTICE
While the procedures for managing files differ from operating system to operating
system, many of the concepts and commands behind the procedures are the same. These
essential commands are examined below.
Creating Files/Folders
In order for a file to exist, it must be created, and thus saved to the disk. Normally, this is
done in a program by saving the file currently being edited. It is also possible in
Windows to right-click a folder anywhere and select an option to create a new empty file.
This is only possible for certain file types that have been programmed into the operating
system (like text files), or when a specific program has made the command available to
the operating system.

Right-clicking to create a file folder: Windows
File naming
While in theory you could name a file anything you like, there are certain conventions to
be followed, as well as limitations.
 A file's name should easily identify its content. I.e., "Letter" is a pretty ambiguous file
name, while "Letter to Mom (March 16)" is much more descriptive.
 A file name must have a file extension, to associate it with a particular program.
Though, as described above, in default installs of some operating systems (like Windows
XP), these extensions won't be immediately visible.
 File names in Windows cannot be longer than 255 characters, and cannot contain the
characters: / : * ? " < > |
Save As
The Save as command saves a new copy of the file currently being edited, but under a
new name. This is very handy for creating several versions of a document, prior to

making edits. Simply save the current state of the document, then select Save As, and
save a new version in which to carry out your edits. If you don't like the way the edits are
going, you can always go back to the file containing the version of the document prior to
the edits.
Copy
Copy, paste, and cut are incredibly handy commands. Mostly used for file editing, they
also can be used for managing files. When you copy a file, it is placed into a specific part
of your computer's memory (called the Clipboard), and can then be pasted into any folder
or drive that you can access from your computer. When you copy a file, the original file
remains untouched.
Paste
When you paste, you create a new copy of whatever file is saved into the operating
system's Clipboard memory. The pasted file will always carry the same name as the
original file that was copied-unless it is pasted back into the same directory as the
original. In that case, the new copy of the file will have its name modified slightly, to
indicate it is a new copy.
Cut/Move
To cut a file is to copy it into the Clipboard, and then delete it from its current spot on a
drive. You then can paste the file anywhere else you can access from your computer. The
cut and paste combination is also known as moving a file, since all the file's data only
exists in the new spot once it has been cut, and can no longer be found in the old.
Rename
As mentioned previously, naming files is a key part of file management. Another
important part is the ability to change a file's name whenever you like. Reorganization is
essential to managing files, and it is often very useful to rename certain files to help
reorganize the way files or folders are laid out.
Selecting Objects
In order to carry out the file management tasks described previously, you need some way
to indicate to the operating system which files are to be affected. Using the pointer in the
GUI, there are a couple of techniques for selecting files. The first is the click. Click once
on a file, and it becomes highlighted. This means that it is selected, and the operating
system is then waiting for a command from you (like "rename" or "delete") to apply to
the selected object.

Lasso
If you click at a point above or below a group of files, hold down the mouse
button and start dragging the pointer, you will see a rectangular outline begin to
grow between the point you first clicked and the pointer. This is called the lasso.
Any icons "caught" in that lasso will be selected as soon as you release the
mouse button. This is the easiest way to select large numbers of adjacent files in
the same folder.
Lassoing files in Windows

Selecting non-adjacent objects
By holding down the CTRL key while you lasso or click objects to select them,
you can maintain the current selection and select more objects that are not
adjacent.
Selecting non-adjacent files in Windows
Deleting
Just like a paper file can be thrown into the trash (or shredded, or recycled) to get rid of
it, and to clear out space for more files, so too can data files on the computer be deleted to
free up space for other files. There are many different ways to carry out the delete
command, but by far the easiest is to select the files to be deleted, and drag them to the
Recycle bin (called the Trash folder on non-Windows computers). If the Recycle Bin
icon is not visible, you can also press the Delete key on the keyboard.
The Trash folder/Recycle Bin
Files that are in the
Recycle Bin do still take
up space on your

computer, though. So
every now and then you
need to empty this
special folder. Once the
Recycle Bin has been
emptied, the space taken
up by the files is freed
and they are truly gone.
When a file is in the Recycle Bin, it cannot be opened by the operating system.
The Recycling Bin is simply an intermediate place where all deleted files
collect. That way, if you delete something and then decide in a few hours that
you actually needed it, it is a very simple task to restore it from the Recycle Bin.
Intermediate File Management
File management, as you have no doubt guessed, involves a lot more than simply moving
files around from one place to another on the computer and changing names. The
operating system also automates other complicated activities that are indispensable to
managing files and information on the computer.

Searching
There can be times when even the sharpest user forgets where the file that he or she needs
is located. That is when it is time to get the operating system to carry out a search for the
file.
A search for a file scans all storage devices connected to the computer and builds up a list
of any files that match the criteria being searched for. These procedures are slightly
different between Windows and Macintosh computers.
Windows
The following example shows how to search for files on the hard drive using Windows.
The search function is initiated by choosing the Start button, selecting Search and then
following through with the appropriate search criteria. Selecting the Search button
executes the "search".
Step 1: Select type of search. Step 2: Fill in criteria and select "Search".

Completed Search Result!

Windows 10 - File Explorer
File Explorer is the file management application used by Windows operating systems to
browse folders and files. It provides a graphical interface for the user to navigate and
access the files stored in the computer.
The main way to access the File Explorer is by clicking the folder icon in the Taskbar.
After clicking the icon, the File Explorer window will open.
The initial File Explorer window is comprised of the following sections −
 The File Explorer ribbon, which resembles the ribbon featured in Microsoft
Office. The ribbon contains buttons for common tasks to perform with your files
and folders.

 The Navigation Pane gives you access to your libraries of documents and
pictures, as well as your storage devices. It also features frequently used folders
and network devices.
 The Frequent folders section on the right features the folders you’ve worked
with recently to allow for quick access to them.
 The Recent files section in the lower part of the window features files and
documents that you’ve opened recently.
The File Explorer Ribbon
In Windows 10, the File Explorer features a new ribbon toolbar, similar to the one
featured in the recent versions of Microsoft Office. This ribbon contains buttons and
commands for the most common tasks.
The Ribbon features four tabs, each with different commands. Among the tasks you can
perform from the Home tab are −
 Copying and pasting files and folders from one place to another.
 Moving files and folders to another location.
 Copying files and folders to another location.
 Deleting a file or folder permanently or sending it to the Recycle Bin.
 Renaming a file or folder.
 Creating a new folder or other new items.
 Verifying or modifying the Properties of a document or folder.
 Opening a file or folder.
 Different options to select one or various files and folders.
The Share ribbon gives you different options to share your files and folders. For example
−
 E-mailing or messaging a file.
 Compressing (“Zip”) a folder to take less space.
 Printing or faxing documents.
 Sharing with other users or networks.

The View ribbon allows you to change the way Windows displays your files and folders.
Some of the changes you can make here are −
 Adding additional panes to show a preview or details of your files.
 Changing the layout of the files and folders from icons to list, and others.
 Sorting and arranging the contents of your folder.
 Hiding selected folders or files.
The File tab opens a menu with different options like −
 Opening an additional File Explorer window.
 Opening command windows for advanced users.
 Changing or configuring options about how File Explorer behaves.

Working with files
Understanding how to work with files and folders is an important part of using your
computer. Once you understand how files and folder work, you'll use them all the time.
In this lesson, we'll show you the absolute basics of working with files, including how
to open files, move your files into folders, and delete files.
Watch the video below to learn more about using files and folders in Windows.
What is a file?
There are many different types of files you can use. For example, Microsoft Word
documents, digital photos, digital music, and digital videos are all types of files. You
might even think of a file as a digital version of a real-world thing you can interact with
on your computer. When you use different applications, you'll often be viewing,
creating, or editing files.
Files are usually represented by an icon. In the image below, you can see a few different
types of files below the Recycle Bin on the desktop.
What is a folder?
Windows uses folders to help you organize files. You can put files inside a folder, just
like you would put documents inside a real folder. In the image below, you can see some
folders on the desktop.
File Explorer
You can view and organize files and folders using a built-in application known as File
Explorer (called Windows Explorer in Windows 7 and earlier versions).

To open File Explorer, click the File Explorer icon on the taskbar, or double-click any
folder on your desktop. A new File Explorer window will appear. Now you're ready to
start working with your files and folders.
From File Explorer, double-click a folder to open it. You can then see all of the files
stored in that folder.

Notice that you can also see the location of a folder in the address bar near the top of
the window.
To open a file:
There are two main ways to open a file:
 Find the file on your computer and double-click it. This will open the file in its
default application. In our example, we'll open a Microsoft Word document
(BdayInvites.docx), which will open in Microsoft Word.

 Open the application, then use the application to open the file. Once the
application is open, you can go to the File menu at the top of the window and
select Open.

Moving and deleting files
As you begin using your computer, you will start to collect more and more files, which
can make it more difficult to find the files you need. Fortunately, Windows allows you to
move files to different folders and delete files you no longer use.
To move a file:
It's easy to move a file from one location to another. For example, you might have a file
on the desktop that you want to move to your Documents folder.
1. Click and drag the file to the desired location.
2. Release the mouse. The file will appear in the new location. In this example, we
have opened the folder to see the file in its new location.

You can use this same technique to move an entire folder. Note that moving a folder
will also move all of the files within that folder.
To create a new folder:
1. Within File Explorer, locate and select the New folder button. You can also
right-click where you want the folder to appear, then select New > Folder.

2. The new folder will appear. Type the desired name for the folder and press
Enter. In our example, we'll call it School Documents.
3. The new folder will be created. You can now move files into this folder.

To rename a file or folder:
You can change the name of any file or folder. A unique name will make it easier to
remember what type of information is saved in the file or folder.
1. Click the file or folder, wait about one second, and click again. An editable text
field will appear.
2. Type the desired name on your keyboard and press Enter. The name will be
changed.
You can also right-click the folder and select Rename from the menu that appears.

To delete a file or folder:
If you no longer need to use a file, you can delete it. When you delete a file, it is moved
to the Recycle Bin. If you change your mind, you can move the file from the Recycle Bin
back to its original location. If you're sure you want to permanently delete the file, you
will need to empty the Recycle Bin.
1. Click and drag the file to the Recycle Bin icon on the desktop. You can also click
the file to select it and press the Delete key on your keyboard.

2. To permanently delete the file, right-click the Recycle Bin icon and select Empty
Recycle Bin. All files in the Recycle Bin will be permanently deleted.
Note that deleting a folder will also delete all of the files within that folder.

Selecting multiple files
Now that you know the basics, here are a few tips to help you move your files even
faster.
Selecting more than one file
There are a few ways to select more than one file at a time:
 If you're viewing your files as icons, you can click and drag the mouse to draw
a box around the files you want to select. When you're done, release the mouse;
the files will be selected. You can now move, copy, or delete all of these files at
the same time.
 To select specific files from a folder, press and hold the Control key on your
keyboard, then click the files you want to select.

 To select a group of files from a folder, click the first file, press and hold the
Shift key on your keyboard, then click the last file. All of the files between the
first and last ones will be selected.

Selecting all files
If you want to select all files in a folder at the same time, open the folder in File Explorer
and press Ctrl+A (press and hold the Control key on your keyboard, then press A). All
of the files in the folder will be selected.
Ctrl+A is an example of a keyboard shortcut. We'll talk more about these in our lesson
on Keyboard Shortcuts in Windows.
If working with files and folders feels a little tricky right now, don't worry! Like anything
else, working with files and folders is largely a matter of practice. You'll start to feel
more comfortable as you continue using your computer. In the next lesson, we'll talk
about another important concept: how to find files on your computer that you can't easily
locate.
Shortcuts
If you have a file or folder you use frequently, you can save time by creating a shortcut
on the desktop. Instead of navigating to the file or folder each time you want to use it,
you can simply double-click the shortcut to open it. A shortcut will have a small arrow in
the lower-left corner of the icon.
Note that creating a shortcut does not create a duplicate copy of the folder; it's simply a
way to access the folder more quickly. If you delete a shortcut, it will not delete the
actual folder or the files it contains. Also note that copying a shortcut onto a flash drive
will not work; if you want to bring a file with you, you'll need to navigate to the actual
location of the file and copy it to the flash drive.

To create a shortcut:
1. Locate and right-click the desired folder, then select Send to Desktop (create
shortcut).
2. A shortcut to the folder will appear on the desktop. Notice the arrow in the lower-
left corner of the icon. You can now double-click the shortcut to open the folder at
any time.
You can also hold the Alt key on your keyboard, then click and drag the folder to the
desktop to create a shortcut.
Finding Files on Your Computer
Finding files on your computer
In the previous lesson, we talked about how folders can help to keep your files
organized. However, there may be times when you have trouble finding a certain file. If
this happens to you, don't panic! The file is probably still on your computer, and there are
a few simple ways to find it. In this lesson, we'll show you different techniques you can
use to find your files, including searching and looking in common places.

Watch the video below to learn more about finding files in Windows.
Common places to look for files
If you're having a difficult time finding a file, there's a good chance you can find it in one
of the following places:
 Downloads: By default, your computer will place downloaded files in a specific
folder, known as the Downloads folder. If you're having trouble finding a file you
downloaded from the Internet, such as a photo attached to an email message, this
is the first place you should look. To view the Downloads folder, open File
Explorer, then locate and select Downloads (below Favorites on the left side of
the window). A list of your recently downloaded files will appear.
 Default folders: If you don't specify a location when saving a file, Windows will
place certain types of files into default folders. For example, if you're looking for
a Microsoft Word document, you could try looking in the Documents folder. If
you're looking for a photo, try looking in the Pictures folder. Most of these
folders will be accessible on the left side of the File Explorer window.

 Recycle Bin: If you deleted a file by mistake, it may still be in the Recycle Bin.
You can double-click the Recycle Bin icon on the desktop to open it. If you find
the file you need, click and drag it back to the desktop or to a different folder.

Searching for files
Let's say you recently downloaded a few photos that were attached to an email message,
but now you're not sure where these files are on your computer. If you're struggling to
find a file, you can always search for it. Searching allows you to look for any file on
your computer.
To search for a file (Windows 10):
In the Cortana Search Box next to the Start button, type to search for a file. The search
results will appear above the search box.

To search for a file (Windows 8):
Click the Start button to go to the Start screen, then start typing to search for a file. The
search results will appear on the right side of the screen. Simply click a file or folder to
open it.

To search for a file (Windows 7 and earlier):
Click the Start button, type the file name or keywords with your keyboard, and press
Enter. The search results will appear. Simply click a file or folder to open it.

Tips for finding files
If you're still having trouble finding the file you need, here are some additional tips.
 Try different search terms. If you're using the search option, try using different
terms in your search. For example, if you're looking for a certain Microsoft Word
document, try searching for a few different file names you might have used when
saving the document.
 Open the last application used to edit the file. If you know you used a certain
application to edit a file, open that application and select File > Open > Recent
from the menu. The file may appear in the list of recently edited files.
 Move and rename the file after finding it. Once you've located the file, you
may want to move it to a related folder so you can find it more easily in the
future. For example, if the file is a picture, you might move it to your Pictures
folder. You may also want to give it a file name that will be easy to remember.
You can review our lesson on Working with Files to learn more about managing
files.
Common Computer Tasks
Common computer tasks
Learning how to use a computer can feel overwhelming at times. Fortunately, there are
some common computer skills that will work the same way in almost any situation.

Once you learn how to use these skills, you'll be able to use them to perform a variety of
tasks on your computer. In this lesson, we'll talk about some common commands you can
use in almost any application, including cut, copy, paste, and undo.
The Menu bar
Most applications have a Menu bar at the top of the window. Each menu has a set of
commands that will perform a specific action within the program. While each
application is different, there are some common commands that work the same way, no
matter which application you're using. Whenever you open a program for the first time,
try clicking these menus to see the various options available.
File menu commands
You'll find the File menu on the leftmost side of the Menu bar in almost every
application. The File menu will usually have the same type of commands. For example,
you can create a new file, open an existing file, and save the current file, among other
functions.

Cut, copy, and paste
Many applications allow you to copy items from one place and then paste them to
another. For example, if you're working with a word processor, you might copy and paste
text to avoid typing the same thing over and over. If there's something you want to move
from one place to another, you can cut and paste instead.
To copy and paste:
1. Select the item you want to copy. In our example, we'll select a word in a
document.
2. Right-click the mouse and select Copy from the menu that appears. You can also
press Ctrl+C on your keyboard.

3. Locate and right-click the desired location for the item, then select Paste. You can
also press Ctrl+V on your keyboard.
4. The item will be copied to the new location. Notice how the original text that was
copied has not been moved or changed.

To cut and paste:
1. Select the item you want to cut. In our example, we'll select a paragraph of text in
a document.
2. Right-click the mouse and select Cut from the menu that appears. You can also
press Ctrl+X on your keyboard.
3. Locate and right-click the desired location for the item, then select Paste. You can
also press Ctrl+V on your keyboard.

4. The item will be pasted, or moved, to the new location. In our example, we used
the cut and paste commands to move the second paragraph above the first
paragraph.

To copy and paste files:
You can use the cut, copy, and paste commands for a variety of tasks on your computer.
For example, if you wanted to create a duplicate copy of a file, you could copy it from
one folder to another.
1. Right-click the file and select Copy from the menu that appears. You can also
press Ctrl+C on your keyboard.

2. Locate and right-click the new location, then select Paste. You can also press
Ctrl+V on your keyboard. In our example, we'll paste the file to the desktop.
3. The duplicate file will appear. Notice how the original file has not been moved or
changed. Also, note that if you make a change to the original file, it will not
update any copies of that file.

Copying a file is not the same as creating a shortcut. You can review our lesson on
Working with Files to learn more about using shortcuts.
Undoing changes
Let's say you're working on a text document and accidentally delete some text.
Fortunately, you won't have to retype everything you just deleted! Most applications
allow you to undo your most recent action when you make a mistake like this. Just
locate and select the Undo command, which is usually in the upper-left corner of the
window near the Menu bar. You can also press Ctrl+Z on your keyboard. You can
continuing using this command to undo multiple changes in a row.

Note that the Undo command will work almost all of the time, but not in every situation.
For example, if you empty the Recycle Bin to permanently delete a file, you can't undo
the action.
Now you know some of the most commonly used commands, which you'll be able to use
in almost any application on your computer. As we mentioned earlier in this lesson, you
can also use keyboard shortcuts to perform these commands even faster. We'll talk
more about keyboard shortcuts in our lesson on Keyboard Shortcuts in Windows.
Adjusting Your Settings
Adjusting your settings
At some point, you may want to adjust your computer's settings. For example, you might
want to change your desktop background or modify your Internet settings. You can
change these settings and more from the Control Panel.
However, in Windows 10, the Control Panel has mostly been replaced by the Settings
app. The Control Panel is still available, but most of the tasks and settings are now also
located in the Settings app.
To open the Settings app (Windows 10):
Click the Start button, then select the gear icon.

To open the Control Panel (Windows 10):
Right-click the Start button, then select Control Panel.
To open the Control Panel (Windows 8):
In Windows 8, you can open the Control Panel directly from the Start screen. Using your
keyboard, type Control Panel and press the Enter key.

To open the Control Panel (Windows 7 and earlier):
1. Click the Start button, then select Control Panel.
2. The Control Panel will appear. Simply click a setting to adjust it. In this example,
we'll click Change desktop background to choose a new wallpaper for our
desktop.

Adjusting application settings
You'll also be able to change the settings for different applications on your computer.
You will usually find application settings under File > Options, Tools > Options, or
within a separate Settings menu. Keep in mind that the location will vary, and some
applications may not have any settings you can change.

Understanding User Accounts
Understanding user accounts
A user account allows you to sign in to your computer. By default, your computer
already has one user account, which you were required to create when you set up your
computer. If you plan to share your computer with others, you can create a separate user
account for each person.
Why use separate user accounts?
At this point, you may be wondering why you would even need to use separate user
accounts. But if you're sharing a computer with multiple people—for example, with your
family or at the office—user accounts allow everyone to save their own files, preferences,

and settings without affecting other computer users. When you start your computer, you'll
be able to choose which account you want to use.
Administrator, Standard, and Managed accounts
Before you create new user accounts, it's important to understand the different types.
 Administrator: Administrator accounts are special accounts that are used for
making changes to system settings or managing other people's accounts. They
have full access to every setting on the computer. Every computer will have at
least one Administrator account, and if you're the owner you should already have
a password to this account.
 Standard: Standard accounts are the basic accounts you use for normal everyday
tasks. As a Standard user, you can do just about anything you would need to do,
such as running software or personalizing your desktop.
 Standard with Family Safety: These are the only accounts that can have
parental controls. You can create a Standard account for each child, then go to
the Family Safety settings in your Control Panel to set website restrictions, time
limits, and more.
Generally, it's safer to be signed in to a Standard account than an Administrator account.
If you're logged in as an Administrator, it may actually make it easier for an
unauthorized user to make changes to your computer. Therefore, you may want to
create a Standard account for yourself, even if you're not sharing the computer with
anyone. You'll still be able to make Administrator-level changes; you'll just need to
provide your Administrator password when making these changes.
Adding and managing user accounts
The process for adding and managing user accounts is quite different for each version of
Windows. To learn more about adding and managing user accounts, review the
appropriate lesson from these Windows tutorials:

 Windows 10: Managing User Accounts and Parental Controls
 Windows XP: Managing User Accounts
Switching between user accounts
If you have multiple user accounts on your computer, it's easy to switch between users
without signing out or closing your current apps. Switching users will lock the current
user, so you won't need to worry about someone else accessing your account.
To switch between user accounts (Windows 10):
Click the current user icon on the left side of the Start menu, then select the desired
user from the drop-down menu. The user will then need to enter a password to sign in.

Click the current user in the upper-right of the Start screen, then select the desired
user from the drop-down menu. The user will then need to enter a password to sign in.
You can switch back by selecting the desired user from the drop-down menu. You'll
need to re-enter your password to unlock the account.

Click the Start button, click the arrow next to Shut Down, and select Switch user.

If you're finished using the computer, you can also choose to log off. This will allow
other users to sign in to the computer with different accounts.

Keyboard Shortcuts in Windows
Keyboard shortcuts in Windows
Keyboard shortcuts are keys or a combination of keys you can press on your keyboard
to perform a variety of tasks. Using keyboard shortcuts is often faster than using a
mouse because you can keep both hands on the keyboard. Keyboard shortcuts are also
universal, which means you can use many of the same shortcuts in a variety of
applications. For example, you can use the shortcuts to copy and paste text in a word
processor and in a web browser.
Watch the video below to learn more about keyboard shortcuts in Windows.
Using shortcuts
Many keyboard shortcuts require you to press two or more keys in a specific order. For
example, to perform the shortcut Ctrl+X, you would press and hold the Ctrl key, then
press the X key, then release.
You'll use the Ctrl (Control) or Alt key to perform most keyboard shortcuts. You'll find
these keys near the bottom-left corner of your keyboard.

Working with text
These keyboard shortcuts are useful when working with text in word processors, email
applications, and more. They can help you perform commonly repeated tasks, like
copying and pasting text.
 Ctrl+X: Cut the selected text.
 Ctrl+C: Copy the selected text.
 Ctrl+V: Paste the copied or cut text.
 Ctrl+A: Select all of the text on the page or in the active window.
 Ctrl+B: Bold the selected text.
 Ctrl+I: Italicize the selected text.
 Ctrl+U: Underline the selected text.
Working with files and applications
You can use keyboard shortcuts to open, close, and switch applications. When working
with a file, like a Microsoft Word document, shortcuts can be used to create new files,
find words, and print.
 Ctrl+Alt+Delete: Force an unresponsive or frozen program to quit. This
keyboard shortcut opens the Task Manager. You can then select the
unresponsive application and close it.

 Delete: Send a selected file or files to the Recycle Bin.
 Enter: Open a selected application or file.
 Ctrl+N: Create a new file.
 Ctrl+O: Open an existing file.
 Ctrl+S: Save the current file.
 Ctrl+Z: Undo the previous action. If you want to redo the action, press Ctrl+Y.
 Windows key: Open the Start menu (or the Start screen in Windows 8).
Internet shortcuts
Keyboard shortcuts can also be used to navigate your web browser. Many of the text
shortcuts above are also useful online, like the shortcuts for selecting, copying, and
pasting text into your web browser's address bar. Note that some of these shortcuts may
work a bit differently depending on the web browser you're using.
 Ctrl+N: Open a new browser window.
 Ctrl+T: Open a new browser tab.

 Ctrl+D: Bookmark the current page.
 Ctrl+B: View bookmarks.
 Ctrl+J: View recently downloaded files.
Using the Alt key to navigate menus
When you press the Alt key, you will have access to all of the menus in the current
application. This means you can perform almost any task with just your keyboard. For
example, you can type Alt+F+X to quit an application. When performing these shortcuts,
you will not need to hold down the Alt key.

Finding more keyboard shortcuts
In many applications, you'll find keyboard shortcuts next to menu items.
In some applications, you may need to hover over a button to display its keyboard
shortcut.

TYPES OF FILES
a) Master Files
They hold permanent data for use in applications such as stock control and
credit control. Usually much of the data items in these files do not change
frequently or with each transaction, e.g. name, address or date of birth.
b) Transaction files
These are also called movement files. They hold temporary records of values.
They are used to update the master file and are overwritten after the updating
of the master file. Examples of Transaction files:
 A customer order file or records, each of which has data on a particular
order.
 A time sheet data file that contains records, each of which has data on
the number of hours worked by a particular employee.
 A stock transaction file that contains records of stock additions or
removals – one record for each movement.
c) Look up files
They are reference files from which such information as prices list and mailing
list can be obtained.
d) Archive files
These are files that are used to store information that has not been in use in the
recent past and would not be in use in the near future – so are used to store
historical data.
e) Backup files
These are copies of transaction files and master files held for security purposes
f) Transition files
Derived from a transaction file by the addition or deletion or ammendment of
data. It is produced as a temporary file during data processing often by the
addition of master file information to a transaction file prior to updating or
output. Examples of transition files:
 An employee time sheet transaction file which has had employee
names added (from an employee master file) and re-sorted into
department order
 A customer order transaction file to which the price of each item
ordered has been taken from a (computerised) catalogue and added
FILE PROCESSING

 Is the process of updating the records in a file to accurately reflect changes
in the data?
 It can be a manual process where procedures are in place to update forms,
which are sent to the respective person responsible for the update.
 It can also be a computerized process where information is first stored in
transaction files until the master file is updated.
FILE PROCESSING METHODS:
1. BATCH PROCESSING is execution of a series of programs ("jobs") on a computer
without manual intervention.
 Batch jobs are set up so they can be run to completion without manual
intervention, so all input data is preselected through scripts or command-
line parameters. This is in contrast to "online" or interactive programs
which prompt the user for such input. A program takes a set of data files
as input, process the data, and produces a set of output data files. This
operating environment is termed as "batch processing" because the input
data are collected into batches on files and are processed in batches by the
program. Batch Processing
 Transactions are collected and processed in batches [groups].
 Transaction processing in which transactions are gathered and
stored for later execution.
 E.g. a supermarket chain operates 5 outlets. At the end of the day
all information on sales [transaction file] is collected, & the main
records [master file] are updated with the sales for that day.
 Performs a group of tasks all at once, while requiring little [or no]
interaction with the user.
 It is a great time saver because the computer can perform repetitive
functions quickly & consistently.
Benefits
Batch processing has these benefits:
 It allows sharing of computer resources among many users and programs,
 It shifts the time of job processing to when the computing resources are less busy,
 It avoids idling the computing resources with minute-by-minute mannual
intervention and supervision,
 By keeping high overall rate of utilization, it better amortizes the cost of a
computer, especially an expensive one.
COMMON BATCH PROCESSING USAGE
 Data processing
 A typical batch processing procedure is End of day-reporting (EOD), especially
on mainframes. Historically systems were designed to have a batch window

where online subsystems were turned off and system capacity was used to run
jobs common to all data (accounts, users or customers) on a system. In a bank, for
example, EOD jobs include interest calculation, generation of reports and data
sets to other systems, print (statements) and payement processing.
 Printing
 A popular computerized batch processing procedure is printing. This normally
involves the operator selecting the documents they need printed and indicating to
the batch printing software when, where they should be output and priority of the
print job. Then the job is sent to the print queue from where printing daemon
sends them to the printer.
 Databases
 Batch processing is also used for efficient bulk database updates and automated
transaction processing, as contrasted to interactive online transaction processing
(OLTP) applications.
 Images
 Batch processing is often used to perform various operations with digital images.
There exist computer programs like Batch Image Processor that let one resize,
convert, watermark, or otherwise edit image files.
 Converting
 Batch processing is also used for converting a number of computer files from one
format to another. This is to make files portable and versatile especially for
proprietary and legacy files where viewers are not easy to come by.
 Job scheduling
 UNIX utilizes cron and at facilities to allow for scheduling of complex job scripts.
Windows has a job scheduler. Most high-performance computingclusters use
batch processing to maximize cluster usage.
2. REAL-TIME PROCESSING,
A real-time operating system (RTOS) OR REAL-TIME PROCESSING is a
multitaskingoperating system intended for real-time applications. Such applications
include embedded systems (programmable thermostats, household appliance controllers),
industrial robots, spacecraft, industrial control (see SCADA), and scientific research
equipment.
A RTOS facilitates the creation of a real-time system, but does not guarantee the final
result will be real-time; this requires correct development of the software. An RTOS does
not necessarily have high throughput; rather, an RTOS provides facilities which, if used
properly, guarantee deadlines can be met generally or deterministically (known as soft or
hard real-time, respectively). An RTOS will typically use specialized scheduling
algorithms in order to provide the real-time developer with the tools necessary to produce
deterministic behavior in the final system. An RTOS is valued more for how quickly
and/or predictably it can respond to a particular event than for the amount of work it can
perform over a given period of time. Key factors in an RTOS are therefore a minimal
interrupt latency and a minimal thread switching latency.

 An early example of a large-scale real-time operating system was
Transaction Processing Facility developed by American Airlines and IBM
for the Sabre Airline Reservations System.
 Real-time Processing
 The master records are updated as and when the transactions
occur.
 A form of transaction processing in which each transaction is
executed as soon as complete data becomes available for the
transaction.
 A supermarket chain would be linked by a network to a main
computer.
 Each time a sale is made the stock information is updated and the
sale information is also updated.
 It is expensive and complicated.
 Record and file locks are implemented to avoid problems with
real-time processing.
3. ONLINE PROCESSING, or OLP, refers to a class of systems that facilitate and
manage transaction-oriented applications, typically for data entry and retrieval transaction
processing. The term is somewhat ambiguous; some understand a "transaction" in the
context of computer or database transactions, while others (such as the Transaction
Processing Performance Council) define it in terms of business or commercial
transactions. OLP has also been used to refer to processing in which the system responds
immediately to user requests. An automatic teller machine (ATM) for a bank is an
example of a commercial transaction processing application.
 The technology is used in a number of industries, including banking,
airlines, mailorder, supermarkets, and manufacturing. Applications
include electronic banking, order processing, employee time clock
systems, e-commerce, and eTrading. The most widely used OLP system is
probably IBM'sCICS.
 Online processing
 A general term for when one computer is interacting directly and
simultaneously with another computer. Many sources of
information are available online.
 Available for immediate use.
 The master file is updated with the transactions through some
form of communication link.
 All real-time processing involves online processing.
 Not all online processing needs to be real-time.
 Require interaction of the user.
Benefits
 Online Processing has two key benefits: simplicity and efficiency. Reduced paper
trails and the faster, more accurate forecasts for revenues and expenses are both
examples of how OLP makes things simpler for businesses.

Disadvantages
 As with any information processing system, security and reliability are
considerations. Online transaction systems are generally more susceptible to
direct attack and abuse than their offline counterparts. When organizations choose
to rely on OLP, operations can be severely impacted if the transaction system or
database is unavailable due to data corruption, systems failure, or network
availability issues. Additionally, like many modern online information technology
solutions, some systems require offline maintenance which further affects the
cost-benefit analysis.
 Centralized processing
 An information system where all critical data and programs are
stored on one main computer, usually a mainframe. Unlike the
task-sharing concept of a client/server system, the central
computer retains all the brains and brawn.
 A computing environment in which all processing takes place on a
mainframe or central computer.
 Puts all processing and control authority within one computer to
which all other computing devices respond.
 Distributed Processing
 The ability to have several computers working together in a
network, where each processor runs different activities for a user,
as required.
 Computers connected together by a communications network. Data
processing occurs on each of the computers, unlike a centralized
processing system in which terminals are connected to a host
computer that performs all of the data processing.
 Use of computers at various locations, typically interconnected via
communication links for the purpose of data access and/or transfer.
 A computer system in which processing is performed by several
separate computers linked by a communications network. The term
often refers to any computer system supported by a network, but
more properly refers to a system in which each computer is chosen
to handle a specific workload, and the network supports the system
as a whole.
 Offline processing
 When your computer performs an operation when it is not
connected to any other computers, it is working offline.
 Means that your computer is not currently connected to an Internet
server.
 Not connected (to a network). Not available to the network
 Time sharing
 A way of sharing out computer facilities between a number of
people who want to use the computer at the same time. Each has a
separate terminal and gets the impression that they have sole use

of the computer with their own 'account'. Similar to
NETWORKING.
 Transaction processing
o A type of computer processing in which the computer responds
immediately to User requests, with each User interaction considered to
be a transaction. Automatic teller machines for banks are probably the
best-known example.
o In computer science, transaction processing is information processing
that is divided into individual, indivisible operations, called
transactions. Each transaction must succeed or fail as a complete unit;
it cannot remain in an intermediate state.
Master file is the main information source in any type of
organization.
File processing is the update of the master file [actual
records] through manual or computerized methods.
FILE ORGANIZATION METHODS & ACCESS
 File Organization-Is the arrangement of data records on storage media
 It determines the manner in which individual records can be accessed or
retrieved
i. Serial file organization
ii. Sequential file organization
iii. Indexed sequential file organization
iv. Direct file organization
v. Inverted file organization
i. SERIAL FILE ORGANISATION
 Is one where records are not stored in any particular order
 They are stored in the order in which they are received
 New records are added at the end of the files
 This method of file organization is used when
- the usage of the records is not clearly known
- as a means of recording transaction as they happen
- as dump files reflecting the physical layout of a file
- as a prelude to organizing the file in another order i.e. transactions may be
punched and stored on a serial file, the file may be subsequently be stored
into a desired sequence
- gives maximum utilization of space
- no room is left for inserting other records
- does not cater for direct access to records
- used on magnetic tapes
- popular on output files, archive files, security files

i. SEQUENTIAL FILE ORGANISATION
- records are arranged in a pre-determined sequence determined by the
primary key
- appropriate for files which are store on tape or disk
- nor generally used for online system that demand fast response
- mainly used for batch processing applications
- suitable when there is for little file enquiry
- can be used for variable length records as well as fixed length records
- waste space as some space is left of reserved for other records to be
inserted in order to preserve the order or organization
 UPDATING
 Updating on tape is carried out in batch mode by reading the whole file
and rewriting it after necessary modification on to a new file.
 On disk can be carried out without rewriting the whole file.
 RETRIEVAL
 Retrieval of a record from a sequential file on tape media can be made
only in the sequential mode by reading all the records in sequence till the
desired record is reached.
 Retrieval of a record from a sequential file on direct access media (DISK)
can be made by using sequential reach skip search, binary search.
 HIT RATE
 In a batch processing run: The proportion of the number of records
processed during a run to the total number of records on the file is called a
hit rate.
 The higher the volatility and the lower the frequency of updating,, the
higher the hit rate.
 PROCESSING OF SEQUENTIAL FILES
 Tapes provides for only serial access
 Disks can be accessed in a serial order or random order.
iii) INDEXED SEQUENTIAL FILES
 Records are stored in sequence but in addition an index is provided to enable
individual records to be located directly after reading the index.
 Records are pointed to by indexes.
 Used with disks only not with magnetic tapes.
 Wastes space.
 The index may be ignored and the data is read sequentially
 The file may be accessed sequentially but using the index to skip over unwanted
records =selective sequential access
 Index may be read into memory and used to obtain data randomly.
 Records can be accessed sequentially OR randomly.
iv) DIRECT FILE ORGANISATION

 Files are stored or haphazardly and an address key is used as reference.
 Records are physically located at an address that is calculated from its
primary key field.
 The calculation of the address from the key field is called hashing.
 Records are scattered on the storage disk instead of being arranged next to
one another or linked via a pointer field.
 Records can rapidly be retrieved and accessed directly
 Used on magnetic disks (e.g. floppies, hard disk) and optical disks.
 Costly in terms of device used and space.
v) INVERTED FILE ORGANISATION
 special case of indexed sequential organization
 an index is maintained for every attribute in the record
 the main file itself may not be stored if direct queries are not to be handled
 the entire file data is, in any case, stored in the indexes
 Useful for handling inverted queries.
vi) MULTI-RING FILE ORGANISATION
 useful for handling inverted query when sets of records have same
attribute value
 Each set of records with same attribute values is linked into a ring.
 A ring of records is a chain where the last in the chain points to the first.
 One of the records is anchored to the index so that it provides an entry
point into the ring.
 The index of the attribute is read first to retrieve records with a particular
attribute value.
 All records with that attribute value can be located.

DATA TRANSMISSION
Definition Data Transmission:
 When we enter data into the computer via keyboard, each keyed element is encoded by the
electronics within the keyboard into an equivalent binary coded pattern, using one of the
standard coding schemes that are used for the interchange of information.
 To represent all characters of the keyboard, a unique pattern of 7 or 8 bits in size is used.
The use of 7 bits means that 128 different elements can be represented, while 8 bits can
represent 256 elements. A similar procedure is followed at the receiver that decodes every
received binary pattern into the corresponding character.
 The most widely used codes that have been adopted for this function are the Extended
Binary Coded Decimal (EBCDIC) and the American Standard Code for Information
Interchange codes (ASCII). Both coding schemes cater to all the normal alphabetic,
numeric, and punctuation characters, collectively referred to as printable characters and a
range of additional control characters, known as non-printable characters.
 Data transmission refers to the movement of data in form of bits between two or more
digital devices.
 This transfer of data takes place via some form of transmission media (for example, coaxial
cable, fiber optics etc.)
Types of Data Transmission
Parallel transmission
 Within a computing or communication device, the distances between different subunits are too
short. Thus, it is normal practice to transfer data between subunits using a separate wire to carry
each bit of data. There are multiple wires connecting each sub-unit and data is exchanged using
a parallel transfer mode. This mode of operation results in minimal delays in transferring each
word.
o In parallel transmission, all the bits of data are transmitted simultaneously on separate
communication lines.
o In order to transmit n bits, n wires or lines are used. Thus each bit has its own line.
• All n bits of one group are transmitted with each clock pulse from one device
to another i.e. multiple bits are sent with each clock pulse.
• Parallel transmission is used for short distance communication.

• As shown in the fig, eight separate wires are used to transmit 8 bit data from
sender to receiver.
Advantage of parallel transmission
 It is speedy way of transmitting data as multiple bits are transmitted simultaneously with a
single clock pulse.
Disadvantage of parallel transmission
 It is costly method of data transmission as it requires n lines to transmit n bits at the same time.
Serial Transmission
 When transferring data between two physically separate devices, especially if the separation is
more than a few kilometers, for reasons of cost, it is more economical to use a single pair of
lines. Data is transmitted as a single bit at a time using a fixed time interval for each bit. This
mode of transmission is known as bit-serial transmission.
• In serial transmission, the various bits of data are transmitted serially one after
the other.
• It requires only one communication line rather than n lines to transmit data
from sender to receiver.
• Thus all the bits of data are transmitted on single line in serial fashion.
• In serial transmission, only single bit is sent with each clock pulse.
• As shown in fig., suppose an 8-bit data 11001010 is to be sent from source to
destination. Then least significant bit (LSB) i,e. 0 will be transmitted first
followed by other bits. The most significant bit (MSB) i.e. 1 will be transmitted
in the end via single communication line.
• The internal circuitry of computer transmits data in parallel fashion. So in
order to change this parallel data into serial data, conversion devices are used.
• These conversion devices convert the parallel data into serial data at the sender
side so that it can be transmitted over single line.
• On receiver side, serial data received is again converted to parallel form so that
the interval circuitry of computer can accept it

• Serial transmission is used for long distance communication.
Advantage of Serial transmission
 Use of single communication line reduces the transmission line cost by the factor of n as
compared to parallel transmission.
Disadvantages of Serial transmission
 Use of conversion devices at source and destination end may lead to increase in overall
transmission cost.
 This method is slower as compared to parallel transmission as bits are transmitted serially one
after the other.
Types of Serial Transmission
 There are two types of serial transmission-synchronous and asynchronous both these
transmissions use 'Bit synchronization'
 Bit Synchronization is a function that is required to determine when the beginning and end
of the data transmission occurs.
 Bit synchronization helps the receiving computer to know when data begin and end during
a transmission. Therefore bit synchronization provides timing control.
Asynchronous Transmission
 Asynchronous transmission sends only one character at a time where a character is either
a letter of the alphabet or number or control character i.e. it sends one byte of data at a time.
 Bit synchronization between two devices is made possible using start bit and stop bit.
 Start bit indicates the beginning of data i.e. alerts the receiver to the arrival of new group
of bits. A start bit usually 0 is added to the beginning of each byte.
 Stop bit indicates the end of data i.e. to let the receiver know that byte is finished, one or
more additional bits are appended to the end of the byte. These bits, usually 1s are called
stop bits.

 Addition of start and stop increase the number of data bits. Hence more bandwidth is
consumed in asynchronous transmission.
 There is idle time between the transmissions of different data bytes. This idle time is
also known as Gap
 The gap or idle time can be of varying intervals. This mechanism is called
Asynchronous, because at byte level sender and receiver need not to be synchronized.
But within each byte, receiver must be synchronized with the incoming bit stream.
Application of Asynchronous Transmission
1. Asynchronous transmission is well suited for keyboard type-terminals and paper tape devices.
The advantage of this method is that it does not require any local storage at the terminal or the
computer as transmission takes place character by character.
2. Asynchronous transmission is best suited to Internet traffic in which information is transmitted
in short bursts. This type of transmission is used by modems.
Advantages of Asynchronous transmission
o This method of data transmission is cheaper in cost as compared to synchronous
e.g. If lines are short, asynchronous transmission is better, because line cost would
be low and idle time will not be expensive.
o In this approach each individual character is complete in itself, therefore if
character is corrupted during transmission, its successor and predecessor character
will not be affected.
o It is possible to transmit signals from sources having different bit rates.
o The transmission can start as soon as data byte to be transmitted becomes available.
o Moreover, this mode of data transmission in easy to implement.
Disadvantages of asynchronous transmission

 This method is less efficient and slower than synchronous transmission due to the overhead
of extra bits and insertion of gaps into bit stream.
 Successful transmission inevitably depends on the recognition of the start bits. These bits
can be missed or corrupted.
Synchronous Transmission
 Synchronous transmission does not use start and stop bits.
 In this method bit stream is combined into longer frames that may contain multiple bytes.
 There is no gap between the various bytes in the data stream.
 In the absence of start & stop bits, bit synchronization is established between sender &
receiver by 'timing' the transmission of each bit.
 Since the various bytes are placed on the link without any gap, it is the responsibility
of receiver to separate the bit stream into bytes so as to reconstruct the original
information.
 In order to receive the data error free, the receiver and sender operates at the same
clock frequency.
Application of Synchronous transmission
o Synchronous transmission is used for high speed communication between computers.
Advantage of Synchronous transmission
 This method is faster as compared to asynchronous as there are no extra bits (start
bit & stop bit) and also there is no gap between the individual data bytes.
Disadvantages of Synchronous transmission
 It is costly as compared to asynchronous method. It requires local buffer storage at
the two ends of line to assemble blocks and it also requires accurately synchronized
clocks at both ends. This lead to increase in the cost.
 The sender and receiver have to operate at the same clock frequency. This requires
proper synchronization which makes the system complicated.
Comparison between Serial and Parallel transmission

Comparison between Asynchronous and Synchronous.
DATA TRANSMISSION MODES
1. SIMPLEX
Data in a Simplex transmission is always one way. Simplex transmission are not often used
because it is not possible to send back error or control signals to the transmit end.
It's like a one-way street. An example of simplex is television, or Radio.

2. HALF DUPLEX
A half-duplex transmission can send and receive in one direction, but not at the same time.
It's like a one-lane bridge where two-way traffic must give way in order to cross. Only one
end transmits at a time, the other end receives. In addition, it is possible to perform error
detection and request the sender to retransmit information that arrived corrupted. In some
aspects, you can think of Internet surfing as being half-duplex, as a user issues a request for
a web document, then that document is downloaded and displayed before the user issues
another request.
Another example of half-duplex is talkback radio, and CB Radio (Citizens Band). You
might have seen movies where a truck driver (drivers of very big trucks) communicates to
each other, and when they want the other person to speak they say "over". This is because
only one person can talk at a time
3. FULL DUPLEX
Data can travel in both directions simultaneously. There is no need to switch from transmit
to receive mode like in half duplex. It like a two lane bridge on a two-lane highway. Have
you ever watched these television talk shows where the host has a number of people on the
show, and they all try to talk at once. Well, that's full duplex!

Of course, in the world of data communications, full duplex allows both way
communications simultaneously. An example can be a consumer, which uses a cable
connection not only, receives TV channels, but also the same cable to support their phone
and Internet surfing. All these activities can occur simultaneously.

DATA COMMUNICATIONS AND
NETWORK BASICS
NETWORKS
 A computer network, often simply referred to as a network, is a collection of
computers and other hardware components interconnected by communication
channels that allow sharing of resources and information Where at least one
process in one device is able to send/receive data to/from at least one process
residing in a remote device, then the two devices are said to be in a network.
Simply, more than one computer interconnected through a communication
medium for information interchange is called a computer network.
 Networks may be classified according to a wide variety of characteristics, such as
the medium used to transport the data, communications protocol used, scale,
topology, and organizational scope.
 Communications protocols define the rules and data formats for exchanging
information in a computer network, and provide the basis for network
programming. Well-known communications protocols include Ethernet, a
hardware and link layer standard that is ubiquitous in local area networks, and the
Internet protocol suite, which defines a set of protocols for internetworking, i.e.
for data communication between multiple networks, as well as host-to-host data
transfer, and application-specific data transmission formats.
 Computer networking is sometimes considered a sub-discipline of electrical
engineering, telecommunications, computer science, information technology or
computer engineering, since it relies upon the theoretical and practical application
of these disciplines.
Properties
Computer networks:
1. Facilitate communications
Using a network, people can communicate efficiently and easily via email, instant
messaging, chat rooms, telephone, video telephone calls, and video conferencing.
2. Permit sharing of files, data, and other types of information
In a network environment, authorized users may access data and information
stored on other computers on the network. The capability of providing access to
data and information on shared storage devices is an important feature of many
networks.
3. Share network and computing resources
In a networked environment, each computer on a network may access and use
resources provided by devices on the network, such as printing a document on a

shared network printer. Distributed computing uses computing resources across a
network to accomplish tasks.
4. May be insecure
A computer network may be used by computer hackers to deploy computer
viruses or computer worms on devices connected to the network, or to prevent
these devices from normally accessing the network (denial of service).
5. May interfere with other technologies
Power line communication strongly disturbs certain forms of radio
communication, e.g., amateur radio. It may also interfere with last mile access
technologies such as ADSL and VDSL.
6. May be difficult to set up
A complex computer network may be difficult to set up. It may also be very
costly to set up an effective computer network in a large organization or
company.
NETWORK TOPOLOGIES
A network topology is the arrangement of elements (such as data links or nodes) in a
network. It is the physical arrangement of terminals in a local area network. The choice
of topology is dependent upon
 type and number of equipment being used
 planned applications and rate of data transfers
 required response times
 cost
Definitions of hub on the Web:
 A common connection point for devices in a network. Hubs are commonly used
to connect segments of a LAN. A hub contains multiple ports. When a packet
arrives at one port, it is copied to the other ports so that all segments of the LAN
can see all packets. A passive hub serves simply as a conduit for the data,
enabling it to go from one device (or segment) to another. ...
 Node – a terminal point in a communications network.
 Workstation – A computer terminal or micro- or minicomputer system designed
to support the work of one person.
MESH TOPOLOGY
 Mesh topology work on the concept of routes.
 In Mesh topology, message sent to the destination can take any possible shortest, easiest route
to reach its destination.

 It works by sending data along the fastest route from one device to another as all devices are
either directly or indirectly connected creating many pathways for data to travel
 Internet employs the Mesh topology and the message finds its route for its destination. Router
works in find the routes for the messages and in reaching them to their destinations.
 It is the topology in which every devices connects to every other device is called a full Mesh
topology unlike in the partial mesh in which every device is indirectly connected to the other
devices.
 In Other topologies like star and bus, messages are usually broadcasted to every computer,
especially in bus topology.
 Similarly in the Ring topology message can travel in only one direction i.e clockwise or
anticlockwise.
Advantages of Mesh Topology
1. Each connection can carry its own data load.
2. It is robust.
3. Extremely fault tolerant
4. Provides security and privacy.
5. Multiple routes for data to travel if one device fails
6. Data can be transmitted from different devices simultaneously. This topology can withstand high
traffic.
7. Even if one of the components fails there is always an alternative present. So data transfer doesn’t
get affected.
8. Expansion and modification in topology can be done without disrupting other nodes.
Disadvantages of Mesh Topology
1. Cabling cost is more. Very expensive
2. Installation and configuration are difficult if the connectivity increases
3. Bulk wiring is required (unless wireless)
4. Expensive
5. Difficult to implement
6. Difficult to administer
7. Difficult to troubleshoot problems like cable faults

8. There are high chances of redundancy in many of the network connections.
9. Overall cost of this network is way too high as compared to other network topologies.
10. Set-up and maintenance of this topology is very difficult. Even administration of the network is
tough.
STAR TOPOLOGY
 Is a network in which nodes are connected to a central component as its hub?
 The central component can be a switching device like a switch or PABX [private automatic
branch exchange], a computer [minicomputer to which workstations or PCs are connected] or
just a wiring center that is a common termination point for the nodes, called a hub.
 A HUB is a component that serves as a common termination point for multiple nodes and that
can relay [store & forward] signals along the appropriate paths.
 All computers are connected to a central device, which provides more resilience for the
network.
 It is the most prevalent topology in use today.

Advantages of star topology
 It is easy to add or remove nodes/workstation
 Because each node has its own link to the central node, the star is more reliable than
other topologies.
 When one system goes down, it does not bring the rest of the network down.
 Easy to install
 Easy to add devices to network
 One break does not bring whole network down
 Easier to troubleshoot
 Widely used
 Centralized management
 Full utilization of resources i.e. printer, sharing of processor
 Direct connection of terminals to the main processor, means that if one terminal
breaks down it won’t affect other terminals.
Disadvantages of star topology
 All traffic between two nodes passes through the central node. If the central
component breaks down, the whole network is down.
 The number of ports of the central component limits the number of connected nodes.
 Costs are usually higher than with bus or ring networks
 If you have only one central device and it fails, it brings the network down
 A star topology requires a lot of cabling since all data path connections must be to the
central node.
 There is no direct communication between or among workstations
 Sharing of processor delays in the processing of jobs.

BUS/LINEAR TOPOLOGY
 Describes a network in which each node is connected to a common line.
 This is also sometimes called a horizontal, multidrop or multi point network.
 Though it is preferable to use the last terms for connections with a
mainframe/minicomputer as in the following diagram.
 In a bus messages travel in both directions and do not go through the individual nodes but
every node can hear each message as it goes past.
 When the signal/message reaches an end of the bus, a terminator absorbs it, to keep it
from traveling back again along the bus line, to avoid interference with other messages
already in the line.
 The data/signals/messages are transmitted in packets along the bus.
 Each packet is send with a receiver identification code that is an address of destination
and all computers on the network are permanently on the alert for any messages coming
to them.
Advantages of Bus Network/topology
 When a node breaks down, the network does not break down.
 A bus uses relatively less cables compared to other topologies
 Direct communication due to direct connection.
 Fast processing since there is no Host computer
 Once a cable has been laid down any new equipment can easily be connected to the
network by a simple tapping into the cable.
 Easy to install
 Costs are usually low
 Easy to add systems to network
 Great for small networks
Disadvantages of Bus Network/topology

 In a bus topology it is not always easy to add a node. [E.g. installation of extra tap in
thick Ethernet].
 Diagnosis/trouble shooting can be difficult.
 Expensive to run [several processors] – Detectors.
 Communication between components of the network traveling in opposite direction along
the bus can collide causing loss of transmitted information.
 Because of this collision a detection system has to be present to control the re-
transmission of lost information thereby making it a more expensive option
 Out-of-date technology
 If cable breaks, whole network is down
 Can be difficult to troubleshoot
 Unmanageable in a large network
 If a malicious user were on this network and utilized a packet capture program, he could
see every conversation that occurred between machines.
RING NETWORK
 A ring network has nodes connected in a circular way.
 Each node has two neighboring nodes
 Data flow is unidirectional.
 A message is forwarded in one direction until it reaches the destination with
intermediate nodes acting as relay [store & forward] units.
 The destination node copies the message and passes the message again to the ring.
 This message then continues to circulate around the ring back to the source.

 A network topology in the form of a closed loop or circle. Each node in the network is
connected to the next, and messages move in one direction around the system. When a
message arrives at a node, the node examines the address information in the message. If the
address matches the node's address, the message is accepted; otherwise the node regenerates
the signal and places the message back on the network for the next node in the system. ...
ADVANTAGES of ring network
 The message return provides the source with a form of acknowledgement. The node
removes its own message from the ring.
 Little cabling needed compared to Star.
 Each node acts as relay unit.
 Packet collisions do not occur because information is traveling in one direction.
 Relatively cheap to install.
 Efficient and accurate means of communication.
 There is no dependency on the host computer or file server as each node controls
transmission to and from itself.
 When the load on the network increases, its performance is better than that of Bus
topology.
 There is no need for network server to control the connectivity between workstations.
 Additional components do not affect the performance of network.
 Each computer has equal access to resource.
 Token ring technology reduces the need of server or central hub to manage the
workstations.

 The message return provides the source with a form of acknowledgement. The node
removes its own message from the ring.
 Little cabling needed compared to Star.
 Each node acts as relay unit.
 Packet collisions do not occur because information is traveling in one direction.
 Relatively cheap to install.
 Efficient and accurate means of communication.
 There is no dependency on the host computer or file server as each node controls
transmission to and from itself.
DISADVANTAGES of Ring Topology
 If one node is disrupted then the whole network goes down.
 Only one machine can transmit on the network at a time.
 The failure of one machine will cause the entire network to fail.
 Adding or removing nodes disrupts the network.
 If one of the nodes breaks down, the whole network will be down.
 If the network cable breaks the whole network is affected
 Adding or removing nodes disrupts the network.
 If one of the nodes breaks down, the whole network will be down.
 If the network cable breaks the whole network is affected
TREE TOPOLOGY
 Also known as Hierarchical Topology, this is the most common form of network
topology in use presently.
 This topology imitates as extended Star topology and inherits properties of bus topology.
 This topology divides the network in to multiple levels/layers of network.
 Mainly in LANs, a network is bifurcated into three types of network devices.
 The lowermost is access-layer where computers are attached.
 The middle layer is known as distribution layer, which works as mediator between upper
layer and lower layer.
 The highest layer is known as core layer, and is central point of the network, i.e. root of
the tree from which all nodes fork.
 All neighboring hosts have point-to-point connection between them.
 Similar to the Bus topology, if the root goes down, then the entire network suffers even
though it is not the single point of failure.
 Every connection serves as point of failure, failing of which divides the network into
unreachable segment.

Advantages of a Tree Topology
 Point-to-point wiring for individual segments.
 Supported by several hardware and software venders.
 Extension of bus and star topologies.
 Expansion of nodes is possible and easy.
 Easily managed and maintained.
 Error detection is easily done.
Disadvantages of a Tree Topology
 Overall length of each segment is limited by the type of cabling used.
 If the backbone line breaks, the entire segment goes down.
 More difficult to configure and wire than other topologies.
 Heavily cabled.
 Costly.
 If more nodes are added maintenance is difficult.
 Central hub fails, network fails.

Tree Topology
HYBRID TOPOLOGY
 A network structure whose design contains more than one topology is said to be hybrid topology.
 Hybrid topology inherits merits and demerits of all the incorporating topologies.
 The diagram below represents an arbitrarily hybrid topology.
 The combining topologies may contain attributes of Star, Ring, Bus, and Daisy-chain topologies.
 Most WANs are connected by means of Dual-Ring topology and networks connected to them are
mostly Star topology networks.
 Internet is the best example of largest Hybrid topology

Advantages of Hybrid Topology
1. Reliable as Error detecting and troubleshooting is easy.
2. Effective.
3. Scalable as size can be increased easily.
4. Flexible.
Disadvantages of Hybrid Topology
1. Complex in design.
2. Costly.

Wireless Network Topology
 Wireless network topology is a logical topology.
 It shows how the computers connect and interact each other when there is no physical
connection, no cables connecting the computers.
 The computers communicate each other directly, using the wireless devices. Wireless
networks can have infrastructure or ad hoc topology.
 The infrastructure wireless network topology is a hub and spoke topology.
 It is also named “one to many” topology.
 There is a single central wireless access point (WAP) in the infrastructure wireless
network topology.
 The ad hoc wireless network topology is a “many to many” topology.
 There is no central access point, every computer of the network communicates
directly with other computer in the ad hoc wireless network topology.

LANs and WANs
There are two types of network: LAN and WAN.
LAN (LOCAL AREA NETWORK)
 LAN is a short form of local area network. Local area network is a network for
connecting computers and other computer accessories with each other.
 Computer accessories include printers, scanners, game consoles etc.
 LAN is used to make the connection of computers within one building.
 To make the connection between the computers we use communication devices and
cables.
 Communication devices are hubs, switches, and routers. Ethernet cables are connected to
hubs, switches, and routers by rj45 ports.
 A LAN is a high-speed data network that covers a relatively small geographic area.
 It typically connects workstations, personal computers, printers, servers, and other
devices.
 LANs offer computer users many advantages, including shared access to devices and
applications, file exchange between connected users, and communication between users
via electronic mail and other applications.
 The development of standard networking protocols and media has resulted in worldwide
proliferation of LANs throughout business and educational organizations.
Local area network (LAN) diagram

What is a virtual local area network (VLAN?)
In a virtual area network, different switches of LAN are logically connected to each other to make
the single switch. This type of network is used to logically differentiate and limit the different
level of computers. For example, there are different departments in the office like the accounting
department, support department, and administrative department. All the computers of these
departments are logically connected to the same switch but one department computer cannot
access another department computer. So same department computers can communicate with each
other but different department computers cannot communicate with each other.
Advantages of local area network (LAN)
Sharing of resources:
All the resources are attached to one network and if any computer needs any resources then it can
be shared with the required computer. Types of resources are the DVD drive, printers, scanners,
modems and hard drives. So there is no need to purchase separate resources for each computer
and it saves money.
Client and server relationship:
All the data from attached computers can be stored in one server. If any computer (Client) needs
data then that computer user can simply log in and access the data from the server. For example
movies and songs can be stored on the server and can be accessed by any authorized user (Client
computer).
Sharing of the internet:
In offices and net cafes, we can see that one internet connection is shared between all computers.
This is also the type of LAN technology in which main internet cable is attached to one server
and distributed amoung attached computers by the operating system.
Software program sharing:
Software programs can also be shared on the LAN. You can use single licensed software and any
user can use it in the network. It is expensive to buy a license for each user in the network so
sharing software program is easy and cost-effective.
Securing of data:
Keeping data on the server is more secure. And if you want to change or remove any data you can
do it easily on one server computer and other computers can access updated data. You can also
give access or revoke access to specific users so that only authorized users can access the data in
the network.
Communication is easy, fast, and time-saving:

In LAN computers can exchange data and messages in the easy and fast way. It also saves time
and makes our work fast. Every user can share messages and data with any other user on LAN.
The user can log in from any computer on the network and access the same data placed on the
server.
Computer identification:
Each computer is given a MAC address and is temporarily stored in the switch or router during
communication. All computers on the LAN are identified by MAC addresses which are used to
send and receive messages and data. Note that MAC address is stored in the network adapter that
is attached in the motherboard of each computer. In old computers, network adapters were not
built in with motherboards but in modern computers, they come built-in with motherboards.
Disadvantages of local area network (LAN)
Data security problem:
If the server computer is not set up correctly and there is a leak in security then unauthorized
users can access the data also. So there should be privacy policy and rules set up correctly on the
server.
Limitation of distance:
Local area networks are usually made within a building or nearby building and cannot extend to
the wider area.
Server crashes may affect all computers:
If any file on the server is corrupted or hard drive fails then all the attached computers face
problems in functioning properly.
Setting up a LAN is expensive:
It is expensive to set up LAN because there is special software required to make a server. Also,
communication devices like hubs, switches, routers, cables are costly. The special administrator is
required to maintain and troubleshoot LAN for a large office.
WAN (WIDE AREA NETWORK)
A network consisting of computers of LAN's connected across a distance WAN can cover small
to large distances, using different topologies such as telephone lines, fiber optic cabling, satellite
transmissions and microwave transmissions. Wide Area Networks (WANs) connect larger
geographic areas. A WAN is a Wide Area Network covering a large geographical area.

Wide area network (WAN) is a type of network that provides transmission of voice, data,
images, and videos over the large geographical area. WAN is made with the
combinations of LAN and MAN. The transmission of data is carried out with the help of
hubs, switches, fiber optics, modem, and routers. To transfer data from any computer
over the internet we use some technologies including:
1. ISDN (Integrated service digital network)
2. SMDS (Switched multimegabit data server)
3. SONET (Synchronous optical network)
4. HDLC (High data link control)
5. SDLC (Synchronous data link control)
6. Frame relay
A WAN is a Wide Area Network covering a large geographical area.

Wide
area network (WAN) diagram

Advantages of a wide area network (WAN)
Covers large geographical area:
Wan covers a large geographical area of 1000 km or more If your office is in different
cities or countries then you can connect your office branches through wan. ISP (Internet
service provider) can give you leased lines by which you can connect different branch
offices together.
Centralized data:
Your company doesn’t need to buy email, files, and backup servers, they can all reside on
head office. All office branches can share the data through the head office server. You
can get back up, support, and other useful data from the head office and all data are
synchronized with all other office branches.
Get updated files and data:
Software companies work over the live server to exchange updated files. So all the coders
and office staff get updated version of files within seconds.
A lot of application to exchange messages:
With IOT (Internet of things) and new LAN technologies, messages are being transmitted
fast. A lot of web applications are available like Facebook messenger, WhatsApp, Skype
by which you can communicate with friends via text, voice and video chat.
Sharing of software and resources:
Like LAN we can share software applications and other resources like a hard drive, RAM
with other users on the internet. In web hosting, we share computer resources among
many websites.
Global business:
Now everyone with computer skills can do business on the internet and expand his
business globally. There are many types of business like a shopping cart, sale, and
purchase of stocks etc.
High bandwidth:
If you get leased lines for your company then it gives high bandwidth than normal
broadband connection. You can get a high data transfer rate that can increase your
company productivity.
Distribute workload and decrease travel charges:
Another benefit of wide area network is that you can distribute your work to other
locations. For example, you have an office in the U.S then you can hire people from any
other country and communicate with them easily over WAN. It also reduces your travel
charges as you can monitor the activities of your team online.

Disadvantages of a wide area network (WAN)
Security problems:
WAN has more security problem as compare to MAN and LAN. WAN has many
technologies combined with each other which can create a security gap.
Needs firewall and antivirus software:
As data transferred on the internet can be accessed and changed by hackers so firewall
needs to be enabled in the computer. Some people can also inject a virus into the
computer so antivirus software needs to be installed. Other security software also needs
to be installed on different points in WAN.
The setup cost is high:
Setting up WAN for the first time in office costs higher money. It may involve
purchasing routers, switches, and extra security software.
Troubleshooting problems:
As WAN covers a lot of areas so fixing the problem in it is difficult. Most of WAN wires
go into the sea and wires get broken sometimes. It involves a lot of resources to fix lines
under the sea. In ISP (Internet service provider) head office many of internet lines,
routers are mixed up in rooms and fixing issues on the internet requires a full-time staff.
Server down and disconnection issue:
In some areas, ISP faces problems due to electricity supply or bad lines structure.
Customers often face connectivity issues or slow Internet speed issues. The solution to
this is to purchase a dedicated line from ISP.
Examples of wide area network (WAN)
Some examples of WAN are below:
 Internet
 U.S defense department
 Most big banks
 Airline companies
 Stock brokerages
 Railway reservations counter
 Large telecommunications companies like Airtel store IT department
 Satellite systems
 Cable companies
 Network providers

ADVANTAGES AND DISADVANTAGES OF NETWORKS
ADVANTAGES OF GROUP WORKING & SHARING RESOURCES OVER A
NETWORK.
ADVANTAGES OF INSTALLING A NETWORK
1. Speed. Networks provide a very rapid method for sharing and transferring files.
Without a network, copying them to floppy disks, then carrying or sending the
disks from one computer to another shares files. This method of transferring files
(referred to as sneaker-net) is very time-consuming.
2. Cost. Networkable versions of many popular software programs are available at
considerable savings when compared to buying individually licensed copies.
Besides monetary savings, sharing a program on a network allows for easier
upgrading of the program. The changes have to be done only once, on the file
server, instead of on all the individual workstations. Low cost. Single device
shared by several machines reduce the need to buy many peripheral devices.
Resource sharing also serves money. An installation can have several low-cost
work stations accessing a single file-server. That puts a lot of processing power
on the user’s desk without the expense of large mainframe systems.
3. Security. Files and programs on a network can be designated as "copy inhibit,"
so that you do not have to worry about illegal copying of programs. Also,
passwords can be established for specific directories to restrict access to
authorized users. Security is good - users cannot see other users' files unlike on
stand-alone machines.
4. Centralized Software Management. One of the greatest benefits of installing a
network at a school is the fact that all of the software can be loaded on one
computer (the file server). This eliminates that need to spend time and energy
installing updates and tracking files on independent computers throughout the
building. Site licenses are likely to be cheaper than buying several stand-alone
licenses.
5. Resource Sharing. Sharing resources is another area in which a network exceeds
stand-alone computers. Some organizations cannot afford enough laser printers,
fax machines, modems, scanners, and CD-ROM players for each computer.
However, if these or similar peripherals are added to a network, they can be
shared by many users. Resource sharing is the primary benefit of networking. It
allows users on different machines to share modems, printers, tape drives and
disk space, for example, users can send network messages requesting to use a
central printer, allowing everyone to share that resource. Users realize the benefit
of sharing information. Data files can be shared between machines on the

network, allowing users to see invoices, results of surveys, company newsletters,
and other information.
6. Electronic Mail. The presence of a network provides the hardware necessary to
install an e-mail system. E-mail aids in personal and professional communication
for all school personnel, and it facilitates the dissemination of general information
to the entire school staff. Electronic mail on a LAN can enable students to
communicate with teachers and peers at their own school. If the LAN is
connected to the Internet, students can communicate with others throughout the
world.
7. Flexible Access. Networks allow data & information access from any computer
in the campus.
8. Workgroup Computing. Workgroup software (such as Microsoft BackOffice)
allows many users to work on a document or project concurrently. For example,
educators located at various schools within a county could simultaneously
contribute their ideas about new curriculum standards to the same document and
spreadsheets.
9. It turns isolated computers into integrated systems, providing an environment
where resources are shared and capacity problems reduced.
10. It allows growth. If more computing resources become a need, a new computer
can be installed, added to the network, and immediately accessed by other
machines and users.
11. High reliability. If applications share data, the data can be replicated across
several machines. If one machine goes down, another can take its place and
provide the data to the applications.
12. A file server is easy to back up as all the data is stored in one place
DISADVANTAGES
Disadvantages of Installing a Network
1. Expensive to Install. Although a network will generally save money over time,
the initial costs of installation can be prohibitive. Cables, network cards, and
software are expensive, and the installation may require the services of a
technician. Purchasing the network cabling and file servers can be expensive.
2. Requires Administrative Time. Proper maintenance of a network requires
considerable time and expertise. Many organizations have installed a network,
only to find that they did not budget for the necessary administrative support.
Increased administration. There will be need for a systems administrator to tune
the network, monitor the network, administer database files, and ensure network
integrity (ensure the network runs smoothly)
3. File Server May Fail. Although a file server is no more susceptible to failure

than any other computer, when the files server "goes down," the entire network
may come to a halt. When this happens, the entire school may lose access to
necessary programs and files.
4. Cables May Break. Some of the configurations are designed to minimize the
inconvenience of a broken cable; with other configurations, one broken cable can
stop the entire network.
5. Security concerns. Some user can gain unauthorized access to private data. There
is a danger of hacking, particularly with wide area networks. Security procedures
are needed to prevent such abuse. Of all the disadvantages, the greatest drawback
is security concerns; therefore, network security is a priority in the development
of network applications.
6. Network failure. As applications increase their use of a network, network failures
become catastrophic.
7. Virus attack. A networked system is vulnerable to destructive network messages.
For example, a message that sparks damaging activity (like erasing files) may
enter the system via the network.Viruses can spread to other computers
throughout a computer network.
8. Managing a large network is complicated, requires training and a network
manager usually needs to be employed.
9. If the file server breaks down the files on the file server become inaccessible. E-
mail might still work if it is on a separate server. The computers can still be used
as stand alones.
NETWORK SECURITY
The field of network security in general and of TCP/IP security in particular is too wide
to be dealt with we take the most common security exposures and measures to counteract
them. Because many, if not all, security solutions are based on cryptographic algorithms.
Security Issues
This section gives an overview of some of the most common attacks on computer
security, and it presents viable solutions to those exposures and lists actual
implementations.
Common Attacks
For thousands of years, people have been guarding the gates to where they store their
treasures and assets. Failure to do so usually resulted in being robbed, neglected by
society or even killed. Though things are usually not as dramatic anymore, they can still
become very bad. Modern day I/T managers have realized that it is equally important to
protect their communications networks against intruders and saboteurs from both inside

and outside. We do not have to be overly paranoid to find some good reasons why this is
the case:
 Tapping the wire: to get access to clear text data and passwords
 Impersonation: to get unauthorized access to data or to create unauthorized e-
mails, orders, etc.
 Denial-of-service: to render network resources non-functional
 Replay of messages: to get access to and change information in transit
 Guessing of passwords: to get access to information and services that would
normally be denied.
 Guessing of keys: to get access to encrypted data and passwords (brute-force
attack, chosen cipher text attack, chosen plaintext attack)
 Viruses, Trojan horses and logic bombs: to destroy data
Though these attacks are not exclusively specific to TCP/IP networks, they should be
considered potential threats to anyone who is going to base his/her network on TCP/IP,
which is what the majority of enterprises, organizations and small businesses around the
world are doing today. Hackers (more precisely, crackers) do likewise and hence find
easy prey.
Observing the Basics
Before even thinking about implementing advanced security techniques such as
the ones mentioned in the following sections, you should make sure that basic
security rules are in place:
 Passwords: Make sure that passwords are enforced to be of a minimum length
(typically six to eight characters), to contain at least one numeric character, to be
different from the user ID to which they belong, and to be changed at least once
every two months.
 User IDs: Make sure that every user has a password and that users are locked out
after several logon attempts with wrong passwords (typically five attempts). Keep the
passwords to superuser accounts (root, supervisor, administrator,etc.) among a very
limited circle of trusted system, network and security administrators.
 System defaults: Make sure that default user IDs are either disabled or have
passwords that adhere to the minimum requirements stated above. Likewise, make
sure that only those services are enabled that are required for a system to fulfill its
designated role.
 Physical access: Make sure that access to the locations where your systems and users
physically reside is controlled appropriately. Information security begins at the
receptionist, not at the corporate firewall.
 Help desk: Make sure that callers are properly identified by help desk representatives
or system administrators before they give out "forgotten" passwords or user IDs.

Social engineering is often the first step to attack a computer network.
Solutions to Security Issues
Therefore, a combination of several such solutions should be considered in order to
guarantee a certain level of safety and security.
 Encryption: to protect data and passwords
 Authentication and authorization: to prevent improper access
 Integrity checking and message authentication codes (MACs): to protect against
the improper alteration of messages
 Non-repudiation: to make sure that an action cannot be denied by the person who
performed it
 Digital signatures and certificates: to ascertain a party's identity
 One-time passwords and two-way random number handshakes: to mutually
authenticate parties of a conversation
 Frequent key refresh, strong keys and prevention of deriving future keys: to
protect against breaking of keys (crypto-analysis)
 Address concealment: to protect against denial-of-service attacks
 Content inspection: to check application-level data for malicious content before
delivering it into the secure network

INTERNET SERVICES
 The Internet is the network of networks being a worldwide collection of
computers that communicate with one another over cables, satellites and optical
fibers. It is literally the whole hardware mass. The Internet is the network used to
transport information.
Internet, by definition is a network of networks that interact with each other through
exchange of data packets. The Internet hosts an enormous information base and
carries numerous information resources and services..
 When we refer to the Internet we are usually talking about the World Wide Web
(WWW) which is the most used feature of the Internet.
 The WWW stores millions of web pages on web servers. These pages can
contain text, pictures, movies, animation and sound. Web pages are written in a
language or code called HTML (Hypertext Markup Language). A set of web
pages is called a website.
 Each web page has its own unique address or URL. The URL will have the
format "http" and a domain (such as ."co.uk"). What goes in between is arbitrary,
but often has the term "www "such as in "http://www.name.co.uk". but it
doesn’t have to (e.g. http://news.bbc.co.uk).
 Most sites have a page that links the user to the other main areas of the site. This
is called the homepage.
 Web pages are connected by hypertext links. When a link is clicked you will be
taken to another page which could be on another server in any part of the world.
 When you move around web pages you are said to be surfing the net. For this you
need a program to read the pages (called a browser), such as Firefox or Internet
Explorer.
 To search for a particular item or topic on the net you use a search engine. There
are many different kinds of search engine, each using slightly different ways of
searching and indexing web content. Google, MSN and Alta Vista are all examples
of search engines, while Yahoo and Exciteare web directories (a bit like the
Yellow Pages phone book) which have a search function built in.
 The World Wide Web Is software that runs on the internet which includes all
documentation that is shared and accessed on the internet.
 A Web page is a document designed to be accessed and read over the WWW. It
must have an address in a recognized format.
DEFINITION OF TERMS

ISPs (Internet Service Providers)
 An ISP is a company that provides access to the Internet to individuals or
companies. ISPs provide local dial-up access from your personal computer to
their computer network and their network connects you to the Internet.
 An institution (usually a private company) that provides access to the Internet in
some form, usually for money.
 A business that delivers access to the Internet.
 Are the companies who provide you with access to the internet. Commonly used
ISPs in Zimbabwe are:
1. PowerTel
2. ZOL
3. Africom
4. Ecoweb
5. Telecel
6. Comone
7. BSAT
8. Brodacom
9. Mweb
Most offer the same basic package of Internet access, email addresses, web space for
your own pages and local rate call charges.
Browser or web browser
 A web browser is a software application that enables a user to display and
interact with HTML documents hosted by web servers or held in a file system.
Popular browsers available for personal computers include Microsoft Internet
Explorer, Mozilla Firefox, Opera, and Safari. A browser is the most commonly
used kind of user agent. The largest networked collection of linked documents is
known as the World Wide Web.
 Is a program that allows you to view the pages on the Web? The most widely
used are
1. Internet Explorer
2. Mozilla Firefox
3. Google chrome
4. Opera
5. Safari
All browsers will have a number of similar features to help you use the Web:
 Forward and back buttons to move between pages
 A history folder which stores details of recently visited web pages
 A stop button if a page is taking too long to load
 Favorites and bookmark options to store often visited pages
 Options to cut, copy, save and print the information viewed
Search engines
 Internet search engines help users find web pages on a given subject. The search
engines maintain databases of web sites and use programs (often referred to as
"spiders" or "robots") to collect information, which is then indexed by the search
engine. Similar services are provided by "directories," which maintain ordered lists of
websites, eg Yahoo!
 Examples of search engines are: Google, MSN, Bing, Yahoo, AltaVista

Internet address
 The numbering system used in TCP/IP internetwork communications to specify a
particular network or a particular host on that network with which to communicate.
Internet addresses are commonly denoted in dotted decimal form.
Examples of internet addresses
1. www.facebook.com
2. www.google.com
3. www.yahoo.com
4. www.gmail.com
5. www.herald.co.zw
IP address
 An IP address (Internet Protocol address) is a unique number, a kind of telephone
number, used by machines (usually computers) to refer to each other when sending
information through the Internet. This allows machines passing the information
onwards on behalf of the sender to know where to send it next, and for the machine
receiving the information to know that it is the intended destination.
List of Internet Terminology
Internet Service Provider: A company, which provides users with an access to the
Internet, is known as an Internet service provider or Internet access provider. ISP, as it is
called, offers email accounts and other services like remote storage of files for its
customers.
Internet Protocol Suite: It is a set of communication protocols, which are used for the
Internet. Transmission Control Protocol (TCP) and Internet Protocol (IP) were the two
pioneering protocols to be introduced in the Internet protocol standard. The Internet
protocol suite is composed of a set of layers wherein; each layer provides a service to the
upper layers in the set. The upper layers deal with abstract data while the lower layer
protocols translate data into physically transmittable forms.
PPP: Point-to-Point protocol (PPP) is a data link protocol that facilitates the
establishment of a direct connection between two nodes on a network.
IP Address: It is a way of numerically identifying an entity on a computer network. The
original addressing system known as IPv4, used 32 bit addresses. With the growth of the
Internet, IPv6 came to be used wherein the addresses are composed of 128 bits.
MAC Address: Media Access Control address (MAC) is the physical hexadecimal
address assigned to each device on a network.
Domain Name System: DNS, as it is called, refers to the hierarchical naming system
used for computers, resources and services on the Internet. It translates the computer
hostnames to IP addresses. By way of the implementation of DNS, the domain name
'www.buzzle.com' translates to its IP address, say, 208.70.178.150. With the help of
DNS, domain names can be assigned to Internet users.

Cyberspace: This term coined by William Gibson, is used to refer to the computer
networks connected to each other and the content they host. It is often used to refer to the
Internet.
WWW: It is a collection of interlinked documents that are accessible over the Internet. It
consists of millions of web pages that contain text, images, voice and videos. Sir Tim
Berners-Lee, a British scientist working at CERN, created the World Wide Web.
Website: A website is a set of web pages consisting of text, audio and video. Web servers
host websites.
URL: It specifies the location of a resource on the Internet. It consists of the basic
address and path.
Web Page: Web pages are resources of information. They are generally created in the
HTML format and provide the web users with navigational abilities through hyperlinks to
other web pages on the web.
Home Page: The term home page is used to refer to the page that is the default page of
any website. It is the main page of a complex website.
Proxy Server: Client machines on a network connect to the proxy server, which forwards
the client requests to other servers and returns responses to the clients.
Web Server: A web server is a computer program that accepts HTTP requests from web
clients and provides them with HTTP responses.
Web Browser: A web browser is a software application that facilitates user interaction
with the text, audio, video and other information that is located on the web.
Cache: Web browsers maintain a cache of recently visited web pages. Some of them use
an external proxy web cache, which is a server program through which web requests
pass. This enables the browsers to cache frequently visited pages. Even search engines
make available already indexed web pages through their caches.
HTTP: Hypertext Transfer Protocol, abbreviated as HTTP, is a communications protocol
used for the transfer of information over the Internet. A client makes an HTTP request
using a web browser to which an HTTP response is sent from the server.
Web Cookie: Also known as an HTTP cookie, it is piece of text that is exchanged
between the web client and the web server. It is sent by the web server to the web client
and returned unchanged by the client each time it accesses the server. You might want to
know how do websites use cookies?

Hyperlink: A reference in a document to another section of the document or to another
document is termed as a hyperlink. Hyperlinks are used to redirect the user from one
section of a page content to another.
Internet security: It is one of the major concerns today. As the Internet acts as a
communication platform that can be accessed by millions of users around the world, it
becomes necessary that proper measures be implemented. Issues like Internet safety that
deal with the content that is made accessible over the Internet are equally important.
Internet privacy relates to safeguarding the privacy of the web users and the sensitive
information on the web from hackers and stalkers.
Email: It is a store-and-forward method of writing, sending and receiving written
messages. Electronic mail is an Internet e-mail system that uses network-based protocols
to exchange messages between network subsystems.
Email Address: It identifies the network location to which an email can be delivered. An
email address is a combination of the user name of the mail user and the host name of the
mailing system. It is of the form, 'username@domain-name'. An email alias is a
forwarding email address. It simply forwards emails to specific email addresses.
Spamming: The act of sending unsolicited bulk messages over an email system is known
as spamming. It is an undesirable use of the electronic messaging systems.
Phishing: It is a fraudulent activity of acquiring the sensitive information by the use of a
fake identity during electronic communication. It is implemented by means of emails and
instant messages wherein a user is lured to enter his/her details, which are actually
captured by a fraudulent website.
Hacking: Hacking is the activity of programmatically gaining access to a computer
application that is otherwise inaccessible. The act of gaining an unauthorized access to a
computer is known as hacking. Hacking of passwords that leads to breach of email
privacy is a threat to communication over the Internet. Internet crime refers to all the
criminal activities that are carried over the Internet.
Email Scams: With the increase in the use of email systems, its security needs also rose.
Fraudulent users started tampering with the email systems to breach security.
Email Virus: It is a computer code that is transmitted through an email in the form of an
attachment. The email attachment causes the destruction of some of the files on the
receiver computer's hard disk and is programmatically emailed to the contacts in the
address book of the receiver.
Email Client: It is also known as a mail user agent (MUA). An email client is a front-end
computer program or an agent that acts as a client for the email server.

Mail Server: It can also be called Mail Transfer Agent (MTA) and is responsible for
receiving incoming email from local users and forwarding outgoing mails for delivery. A
mail server application forms the heart of a messaging system that performs all the
functions to keep the mails moving over the network.
SMTP: Short for Simple Mail Transfer Protocol, SMTP is the standard for the
transmission of electronic mails. The electronic mail server software uses SMTP to send
and receive mail messages. ESMTP, that is known as extended or enhanced SMTP refers
to the protocol extensions made to SMTP and is widely used today.
POP3: Short for Post Office Protocol, POP3 is an application layer Internet standard
protocol. It is used to retrieve mails from a remote server. Here is a brief introduction to
POP3.
IMAP: Internet Message Access Protocol, as it is called, is another Internet standard
protocol used for retrieval of emails.
Internet Chat: It is a real-time Internet chat or synchronous conferencing that is used for
group communication as well as one-to-one communication over the Internet. Jarkko
Oikarinen, a Ph.D. from the University of Oulu is the developer of the first Internet chat
network. He developed the client and server programs for Internet Relay Chat in August
1988.
Social Networking: Social networking is about building online communities of like-
minded people. Serving as an excellent platform for sharing of information, social
networking is a rage today.
ADSL: Asymmetric Digital Subscriber Line, abbreviated as ADSL, is used for the
transmission of digital information using high bandwidths on existing phone lines. ADSL
technology is characterized by high download and low upload rates.
Dial-up: It is the means to connect to the Internet using the copper phone lines and a
modem. Dial-up connections are capable of sending information from the client's end at
very slow speeds of about 56kbps.
Modem: It is a device that modulates analog carrier signals to encode digital information
and demodulates carrier signals to decode information. A cable modem provides access
to data signals sent over the cable television infrastructure. Modems are commonly used
for facilitating Internet access.
Communication Bandwidth: It refers to the data that can be transferred between two
points in a given period of time. It is expressed in terms of bits per second. It is
commonly known as the bit rate.
Blogs: Blogs are the expressions of the common masses about social or political issues or
simply anything. Blogs can often be in the form of creative write-ups by writers in

different parts of the world.
Internet Forums: It is a bulletin board that serves as a platform for group discussion.
Registered users are free to contribute to the issues raised in forums thus making them
open discussion platforms.
Usenet: Usenet can be considered as a worldwide bulletin board. Usenet newsgroups
serve as a repository of messages posted from users around the world.
Internet - A Search Platform
Internet that hosts an ocean of information has also become an excellent platform for
information retrieval. The Internet search engines, which crawl and index web pages,
organize the information on the Internet and the web directories link to information on
the network. Here is a list of the Internet terms related to the Internet as a search
platform.
Internet Search Engine: It is an information retrieval system that is designed to help
find information over the Internet. Search engines use algorithms to scan the huge
information base of the Internet and sort it making it retrievable for the web users.
Search Engine Optimization: The process of organizing the content of a website with
intent to increase its relevance with respect to keywords and search engines. The process
of optimization involves editing website content and HTML coding to support search
engine strategies of ranking and indexing.
Internet Bookmark: The Internet browsers of the modern times aim at enabling the
users to organize the web pages they access. Links once visited can be saved in the
favorites or preferences categories. Bookmarks are usually integrated into browsers.
Social bookmarking is a method used by Internet users to store and manage web pages.
Web Directories: It is a directory, which links to other websites and organizes those
links. They should not be mistaken as being search engines.
OTHER TERMS
Router: A router connects two or more logical subnets and performs the functions of
routing and forwarding information.
Intranet: It is a relatively smaller private network that uses the Internet protocols and
connectivity. It is an extension of the Internet and is privately used by organizations.
Extranet: It is a private network that uses Internet technology to share a part of the
business information and operations with suppliers and customers. It can be a part of a
company's intranet that provides access to the users outside the company.
Virtual Private Network: It is a private network that allows the exchange of information

between computers over a shared or a public network.
Wireless Networking: It refers to computer networking that is carried out over the
wireless media.
Broadband Internet: Broadband connectivity to the Internet provides the users with a
high-speed Internet access.
Dial-up Internet: In this type of access to the Internet, the user's computer is attached to
a modem connected to a telephone line. Dial-up Internet access involves a modem that
dials into an Internet service provider to establish a connection.
Satellite Internet: Internet services that make use of the satellite communication media
are termed as satellite Internet services. They are used in locations that are mobile thus
making terrestrial Internet connectivity, an impossibility.
What are the advantages & disadvantages of the Internet? Discuss
These are far too broad and extending to all realms in life. For instance:-
1) Access to a wide range of information from any location worldwide where
there is internet access. i.e. airlines, resorts, books, authors.
2) Research on any topic i.e. a professor, current affairs.
3) Online Shopping i.e. for cars, specific dress.
4) Online ordering and carrying out other business transactions e.g.. Ordering a
cheque book, advertising a product.
5) Online conferencing – communicating across international boundaries.
6) Ability to access e-mail from any location worldwide.
7) Reading newspapers online.
Advantages
Faster Communication
The foremost target of Internet has always been speedy communication and it has
excelled way beyond the expectations. Newer innovations are only going to make it faster
and more reliable. Now, you can communicate in a fraction of second with a person who
is sitting in the other part of the world. For more personal and interactive communication,
you can avail the facilities of chat services, video conferencing and so on. Besides, there
are plenty of messenger services in offering. With the help of such services, it has
become very easy to establish a kind of global friendship where you can share your
thoughts and explore other cultures.
Information Resources
Information is probably the biggest advantage that Internet offers. Internet is a virtual

treasure trove of information. Any kind of information on any topic under the sun is
available on the Internet. The search engines like Google, Yahoo are at your service on
the Internet. There is a huge amount of information available on the Internet for just
about every subject known to man, ranging from government law and services, trade fairs
and conferences, market information, new ideas and technical support, the list is simply
endless.
Students and children are among the top users who surf the Internet for research. Today,
it is almost required that students should use it for research or the purpose of gathering
resources. Even teachers have started giving assignments that require extensive research
on the Internet. Besides, you can have an access to latest researches in the field of
medicine, technology and so on. Numerous web sites such as America's Doctor also
allow you to talk to the doctors online.
Entertainment
Entertainment is another popular raison d'être why many people prefer to surf the
Internet. In fact, the Internet has become quite successful in trapping the multifaceted
entertainment industry. Downloading games or just surfing the celebrity websites are
some of the uses people have discovered. Even celebrities are using the Internet
effectively for promotional campaigns. Besides, there are numerous games that can be
downloaded for free. The industry of online gaming has tasted dramatic and phenomenal
attention by game lovers.
Social Networking
One cannot imagine an online life without Facebook or Twitter. Social networking has
become so popular amongst youth that it might one day replace physical networking. It
has evolved as a great medium to connect with millions of people with similar interests.
Apart from finding long-lost friends, you can also look for job, business opportunities on
forums, communities etc. Besides, there are chat rooms where users can meet new and
interesting people. Some of them may even end up finding their life partners.
Online Services
The Internet has made life very convenient. With numerous online services you can now
perform all your transactions online. You can book tickets for a movie, transfer funds,
pay utility bills, taxes etc., right from your home. Some travel websites even plan an
Itinerary as per your preferences and take care of airline tickets, hotel reservations etc.
e-commerce
The concept of e-commerce is used for any type of commercial maneuvering or business
deals that involves the transfer of information across the globe via the Internet. It has
become a phenomenon associated with any kind of shopping, business deal etc. You
name a service, and e-commerce with its giant tentacles engulfing every single product
and service will make it available at your doorstep. Websites such as eBay allow you to
even bid for homes, buy, sell or auction stuff online.
Additional advantages

1. Global Audience
Content published on the World Wide Web is immediately available to a
global audience of users. This makes the World Wide Web a very cost-
effective medium to publish information. Reaching more than 190 countries.
2. Operates 24 hours, 7 days a week
You don't need to wait until resources are available to conduct business. From
a consumer's perspective as well as a provider's business can be consummated
at any time. The fact that the Internet is operational at all times makes it the
most efficient business machine to date.
3. Relatively Inexpensive
It is relatively inexpensive to publish information on the Internet. At a fraction
of the cost to publish information by traditional methods, various
organizations and individuals can now distribute information to millions of
users. It costs only a few thousand dollars to establish an Internet presence and
publish content on the Internet.
4. Product Advertising
You can use the World Wide Web to advertise various products. Before
purchasing a product, customers will be able to look up various product
specification sheets and find out additional information. You can use the
multimedia capabilities of the World Wide Web to make available not only
various product specification sheets but also audio files, images, and even
video clips of products in action. The beauty of the Web is that it allows
customers to explore products in as much detail as they desire. If the client
just wants a general overview, he or she can look at the advertising
information. For those wanting more in depth information, you can provide
white papers and product descriptions for download. The Web allows a
business to provide timely information, you can simply place the information
on the Web page and it is available immediately for your customers.
5. Distribute Product Catalogs
The World Wide Web is a very effective medium for distributing product
catalogs. In the old days, putting together a product catalog used to be very
costly in terms of time and money needed to publish and distribute it. The
World Wide Web changes all this by allowing content developers to put
together a sales catalog and make it available to millions of users
immediately. Furthermore, unlike printed product catalogs that are usually
updated around once a month, product catalogs on the World Wide Web can
be updated as needed to respond to various changing market conditions.
6. Online Surveys
Traditional methods of performing surveys are often relatively slow and
expensive compared to online surveys conducted on the Internet. For example,
in order to fill out various needs of customers or what they would like to see
in a future product, it's often necessary to compile a list of address and mail a
questionnaire to many customers. The success of such an attempt is not
always guaranteed and can be very costly in terms of mailing the
questionnaires and entering responses to a databases and analyzing it. On the
other hand, you can use the World Wide Web to automate the whole process.

For example, you can set up a CGI script to conduct online surveys. Results of
such a survey can be automatically updated to a database. This database can
then be used to keep a pulse on various opinions and needs of customers.
7. Announcements
With the World Wide Web, you can distribute various announcements to
millions of users in a timely manner. Because there is virtually no time lag
from the time it takes to publish information to making the information
available to users, the Web is an ideal medium to publicize announcements.
As more people discover the virtues of the Web and get connected to the
Internet, the Web will become the medium of choice for many organizations
and individuals to publicize various announcements.
8. Provide Technical Support
You can also use Web site to provide technical support to users. Because Web
pages can be updated immediately with new information, various technical
support literature can be immediately modified in light of new findings and
developments. This can be accomplished without having to distribute changes
to all users affected by any changes using traditional mediums of information
distribution, which are often quite costly compared to the World Wide Web.
9. Create Online Discussion Forums
By using applications such as WebBoard, it's possible to set up online
discussion forums on the Web.
10. Obtain Customer Feedback
The interactive nature of the World Wide Web is ideal for obtaining customer
feedback. You can easily set up a CGI script to obtain customer feedback
about a product or service. Because customer feedback submitted by
customers can be read immediately, it's possible to respond to various
customer concerns in a timely manner, increasing customer satisfaction and
quality of customer service.
11. Immediate Distribution of Information
When information is added to a Web site, it's immediately available for
browsing by millions of Internet users. The World Wide Web is an ideal
medium of information distribution because it takes away the time lag
associated with publishing content and actually making it available to users
12. Easy Integration with Internal Information Systems
Internet information systems deployed on the Internet can be easily integrated
with internal information systems managed with office productivity
applications such as Microsoft Office.
13. Powerful Content Publishing Tools
A new breed of Internet aware applications will start emerging in software
stores by the time you read this. These applications will enable users to
develop content for the World Wide Web by simply saving as an HTML file.
In addition to software developers making existing applications Internet
aware, various new, powerful, and easy-to use Internet content publishing
applications are also being developed. These applications will make the task
of publishing content on the Internet even easier. Most of these applications
are developed for Windows users.

14. Multimedia
The capability to incorporate multimedia into Web pages is a major advantage
of using World Wide Web to publish information. For example, many Web
sites use sounds and video clips to make the content easier and more
interesting to browse.
15. Formatting Capabilities
Content published on the World Wide Web can be richly formatted by using
various HTML tags and graphic formats. The capability to do this is a major
reason for the success of the World Wide Web. In addition to using HTML
tags and various multimedia formats in Web pages, various interactive
controls can also be added to a web page. This capability allows Web site
content developers to create "active" Web sites. For example, before a user
sends some information to a Web server for processing, a VBScript or
JavaScript subroutine can be used to verify information typed in by the user.
Various formatting capabilities, along with technologies such as Java and
VBScript, make the World Wide Web a richly interactive medium that you
can use to distribute information to millions of users.
Disadvantages
Theft of Personal Information
If you use the Internet for online banking, social networking or other services, you may
risk a theft to your personal information such as name, address, credit card number etc.
Unscrupulous people can access this information through unsecured connections or by
planting software and then use your personal details for their benefit. Needless to say, this
may land you in serious trouble.
Spamming
Spamming refers to sending unwanted e-mails in bulk, which provide no purpose and
needlessly obstruct the entire system. Such illegal activities can be very frustrating for
you as it makes your Internet slower and less reliable.
Virus Threat
Internet users are often plagued by virus attacks on their systems. Virus programs are
inconspicuous and may get activated if you click a seemingly harmless link. Computers
connected to the Internet are very prone to targeted virus attacks and may end up
crashing.
Pornography
Pornography is perhaps the biggest disadvantage of the Internet. Internet allows you to
access and download millions of pornographic photos, videos and other X-rated stuff.
Such unrestricted access to porn can be detrimental for children and teenagers. It can
even play a havoc in marital and social lives of adults.
Social Disconnect
Thanks to the Internet, people now only meet on social networks. More and more people

are getting engulfed in virtual world and drifting apart from their friends and family.
Even children prefer to play online games rather than going out and mingling with other
kids. This may hamper a healthy social development in children
The Web uses three standards namely:
1 URLs (Uniform Resource Locators) – which are web page addresses
2 HTTP (Hypertext Transfer Protocol) – the language used to design web pages
3 HTML (Hypertext Markup Language)
To send e-mail access the Internet, both the sender and receiver need:
WHAT IS NEEDED FOR INTERNET AND E-MAIL SERVICES
1) A computer connected to a network,
2) The windows operating system installed
3) The communication and or browser software such as Ms-Exchange or Ms-
Outlook, Internet explorer, Netscape navigator
4) A modem
5) Telephone line
6) Subscription to an ISP (Internet Service Provider).
What do you need to get connected?
To connect to the internet you need:
1) A computer with windows OS or any other OS
2) A telephone line
PSTN or Public Switched Telephone Network is simply or most commonly known as
a ‘telephone line’. This is the most commonly used method by all users that only have
the need to use one line for one conversation at a time using only one phone number.
PSTN uses an old technology whereby circuit-switched copper phone lines are used
to transmit analogue voice data. It is the basic service that you have at home and in a
small business.
As a dedicated service, a PSTN line cannot be used for any other purpose while a call
is being made. A PSTN phone number is equivalent to one phone line.
3) A MODEM - the type of modem you need to use is dependent on the type of
connection you have. Some of the choices are:
An analogue modem and an ordinary phone line. This type of modem links your

computer to the phone and converts computer signals to analogue phone line signals -
and back again. Typical analogue modem speeds are 56Kbps (bps stands for bits per
second) which means they can receive about 6000 characters per second. This is the
slowest and oldest type of connection and becoming less common with the
introduction of broadband.
An ISDN line and terminal adaptor. This digital connection is slightly faster than an
analogue connection. ISDN or Integrated Services Digital Network provides digital
transmission of voice and data services. Although now it is primarily used for Voice
as it give you the options of having more than one Channel (line). They come in
many ‘flavours’… 2, 10, 20 and 30 and you can also increase the number of Channels
as your business expands by multiple ISDNs to meet your requirements. Medium to
large businesses prefer this product as it gives them the option of integrating it with
their phone systems (PABX) and takes advantage of multiple features. Like using a
100 number range, groups, queues, on hold music and RVAs, etc.
When ISDN was launched it was able to simultaneously support early video
conferencing systems and analogue phone lines. A few years ago ISDN was the
fastest Internet speed available (128 kbps) but its popularity is rapidly declining due
to the introduction of cloud communications.
An ADSL or cable telephone line and broadband modem. Broadband modems are
much faster than the other two options and their use is increasing. ADSL or
Asymmetric Digital Subscriber line or in other words ‘the Internet’. Ok, not quite the
Internet, but it is the means to connect to the Internet. This type of service is most
commonly used by small businesses because it provides enough bandwidth for a
small group of users to access the Internet. It works only over an existing PSTN, so
you need to have an active PSTN to be able to have ADSL.
4) An account with an ISP (Internet Service Provider)
 An ISP is a company that provides access to the Internet to individuals or
companies. ISPs provide local dial-up access from your personal computer to
their computer network and their network connects you to the Internet.
 Are the companies who provide you with access to the internet. Commonly used
ISPs in Zimbabwe are:
10. PowerTel
11. ZOL
12. Africom
13. Ecoweb
14. Telecel
15. Comone
16. BSAT
17. Brodacom
18. Mweb
Most offer the same basic package of Internet access, email addresses, web space for
your own pages and local rate call charges.
5) Browser software

 A web browser is a software application that enables a user to display and
interact with HTML documents hosted by web servers or held in a file system.
Popular browsers available for personal computers include Microsoft Internet
Explorer, Mozilla Firefox, Opera, and Safari. A browser is the most commonly
used kind of user agent. The largest networked collection of linked documents is
known as the World Wide Web.
 Is a program that allows you to view the pages on the Web? The most widely
used are
6. Internet Explorer
7. Mozilla Firefox
8. Google chrome
9. Opera
10. Safari
All browsers will have a number of similar features to help you use the Web:
 Forward and back buttons to move between pages
 A history folder which stores details of recently visited web pages
 A stop button if a page is taking too long to load
 Favorites and bookmark options to store often visited pages
 Options to cut, copy, save and print the information viewed
ELECTRONIC MAIL
 Electronic mail or email is a means of sending messages, text, and computer files
between computers via the telephone network. Because the telephone network
covers the whole world, email enables you to communicate world wide.
Email and web mail
EMAIL
To set up email you need:
 A computer
 An internet connection via an analogue modem (ordinary phone line) or terminal
adaptor (ISDN) or broadband modem (ADSL and cable)
 An account with an ISP (Internet Service Provider)
 Email software
Your Internet Service Provider will give you an email account, a password and a mailbox
such as yourname@hostname.co.uk. You can also set up an email account with a
mailbox and passwords with non-ISPs such as Google and Hotmail.
With a dial-up connection, you have to pay the cost of your internet phone calls (local
rate), and in most cases a subscription to your provider (though some are free). A
broadband connection is 'always on', with only a flat-rate subscription. Very few people
pay by the minute nowadays and the majority of people pay a monthly fee for broadband
access.

Anti-virus scanning is becoming standard on email accounts and many email providers
now offer an anti spam (electronic junk mail) service.
WEB MAIL
Web mail, as its name suggests, is web-based email. To use web mail, you do not need
any email software - just a computer connected to the internet via any one of the
connection types listed above, and a browser.
Users simply sign up to the web mail service of a web portal such as MSN or Yahoo.
They are given a unique user name and a personal mailbox on the portal's email server,
and they can then send and receive messages via a special web page.
A basic web mail account is usually free, although this will have a very limited amount of
storage.
The advantage of web mail is that users can receive and send mail from any computer in
the world with internet access. If you have a dial-up connection you can download your
emails and then read them offline to avoid staying on-line for long periods.
Some ISPs will enable their regular email customers to access their mailbox via web mail
as well as through the email software on their PC.
Features of email
 Automatic reply to messages
 Auto forward and redirection of messages
 Facility to send copies of a message to many people
 Automatic filing and retrieval of messages
 Addresses can be stored in an address book and retrieved instantly
 Notification if message cannot be delivered
 Automatically date and time stamped
 Signatures can be attached
 Files, graphics or sound can be sent as attachments, often in compressed formats
 Web mail and mobile email can be used to receive and send messages while on
the move.
Using email
 Broadband email
- Your connection is always on - so simply write and address your message and
hit 'send' to send your mail and 'receive' to download any incoming messages
from your email provider's server.
 Web mail
- Connect to the internet (if using a dial-up account) and open your browser.
- navigate to your web mail provider's portal and enter your user-name and
password.
-all incoming mail will now be visible, and you can also compose and send mail,
and download attachments to your computer.
- When you're done, log out and close your connection.
 Dial-up email
- Prepare your message offline as typing your message online will increase phone

charges.
- Connect to the internet and log on to your email account.
- Send your message and download any incoming mail sitting on your service
provider's computer.
- Log off and close your connection.
Email is evolving...
 Many mobile phones already allow messages to be sent to the recipient's email
inbox while the sender is on the move. The latest generation of mobile phones
enables users to send and receive wireless email in exactly the same way as a
static computer.
 Email can be sent and received via digital TV, specially adapted phones, public
kiosk terminals and the latest generation of games console.
 A spreading network of wireless 'hotspots' in public places allows people to send
and receive email via laptop computers.
 A new range of in-car phones will enable motorists to check their email on the
road
Benefits and concerns of using email
Email benefits
 Fast delivery of your message
 Available 365 days, 24 hours per day - and, with web mail, wherever you are in
the world as long as you have access to the internet.
 Cheap: when using broadband, individual mail transfers are effectively free.
When going online from a dial-up account, calls are charged at local rates and (for
conventional email) need only last a few seconds.
 Facility to send the same message to more than one person
Email concerns
 It can only be sent to people who themselves have access to the internet.
 Viruses are easily spread via email attachments - anti virus measures must be in
place to avoid this and are now offered by many e-mail providers.
 Phishing - sending an e-mail to a user falsely claiming to be a legitimate
company to scam the user into providing information such as personal
information and bank account numbers on a bogus website. The details will then
be used for identity theft.
 No guarantee the mail will be read until the user logs on and checks their mail.
 Spam! Or Junk mail

COMPUTER ERGONOMICS HEALTH
AND SAFETY
Computer Ergonomics
 Many people spend hours a day in front of a computer without thinking about the
impact on their bodies. They physically stress their bodies daily without realizing
it by extending their wrists, slouching, sitting without foot support and straining to
look at poorly placed monitors.
 These practices can lead to cumulative trauma disorders or repetitive stress
injuries, which create a life-long impact on health. Symptoms may include pain,
muscle fatigue, loss of sensation, tingling and reduced performance.
 Ergonomics is a field of study that attempts to reduce strain, fatigue, and injuries
by improving product design and workspace arrangement. The goal is a
comfortable, relaxed posture.
What Is "Computer Ergonomics"?
Ergonomics is the science of designing a job, equipment and/or workplace to fit the
worker. The goal is to optimize the "fit" between each worker and his or her work
environment to optimize performance and reduce the risk of repetitive strain injuries.
Computer ergonomics addresses ways to optimize your computer workstation to reduce
the specific risks of computer vision syndrome (CVS), neck and back pain, carpal tunnel
syndrome and other disorders affecting the muscles, spine and joints.
Some experts in this field also use the term "visual ergonomics" when talking about
designing a computer workstation with the goal of preventing CVS.
Computer And Visual Ergonomics: OSHA Tips
You don't need an expensive consultant to create a computer workstation that reduces
your risk of stress, discomfort and potential injury.
Here are some of the top computer ergonomics tips recommended by the Department of
Labor's Occupational Safety & Health Administration (OSHA). These tips are designed
to reduce the risk of stress, physical injury and computer eye strain from prolonged
computer use.

TIPS FOR AN ERGONOMIC WORKSTATION
1. Use a good chair with a dynamic chair back and sit back in this
2. Top of monitor casing 2-3" (5-8 cm) above eye level
3. No glare on screen, use an optical glass anti-glare filter where needed
4. Sit at arm’s length from monitor
5. Feet on floor or stable footrest
6. Use a document holder, preferably in-line with the computer screen
7. Wrists flat and straight in relation to forearms to use keyboard/mouse/input device
8. Arms and elbows relaxed close to body
9. Center monitor and keyboard in front of you

10. Use a negative tilt keyboard tray with an upper mouse platform or downward
tiltable platform adjacent to keyboard
11. Use a stable work surface and stable (no bounce) keyboard tray
12. Take frequent short breaks (micro breaks)
With better posture, this computer worker might avoid neck and back strain.
1. Sit so your head and neck are upright and in-line with your torso, not bent down
or tilted back.
2. Face your computer screen directly. Avoid viewing your screen with your head
turned or your back twisted.
3. Keep your elbows comfortably close to your body.
4. Use a chair that provides support for your lower back and has a cushioned seat
with a contoured front edge.
5. Keep your mouse close to your keyboard so you don't have to reach for it.
6. Position your computer display so the top of the screen is at or slightly below eye
level. This will allow you to view the screen without bending your neck.
7. Adjust the position of your display to prevent reflections of overhead and outdoor
lighting appearing on your screen.
8. Put your monitor close enough to your eyes so you can comfortably read text on
the screen without leaning forward.
9. When working with print documents, use a document holder that positions them
at the same height and distance as your computer screen.

10. Use a hands-free headset when talking on the phone while working at your
computer.
Also, adjust the height of your chair and desk so that:
 Your upper arms are perpendicular to the floor, not stretched forward or angled
backward
 Your forearms, wrists and hands form a 90-degree angle with your upper arms
 Your thighs are parallel to the floor and your lower legs are perpendicular to the
floor
 Your wrists and palms are not resting on sharp edges
If you wear bifocals or trifocals, you should be able to comfortably view your computer
screen without tilting your head back. If this is not the case, consider purchasing
computer glasses.
Following these tips will help you avoid stressful postures that lead to headaches, neck
and back pain and computer vision syndrome.
But remember, prolonged computer work — even at an ideal workstation — is stressful
to your body and your eyes.
To relieve stress that can lead to computer vision syndrome and physical disorders, be
sure to take frequent breaks when working at a computer.
Many experts, including optometrists who specialize in computer vision, recommend that
you get up and move away from your computer for short breaks at least every 20 to 30
minutes.
Take a few minutes to stretch your arms and back, and let your eyes relax their focus by
looking at something at least 20 feet away.
Also, blink fully and frequently to reduce your risk of dry eyes from computer use. If
necessary, apply "artificial tear" eye drops to moisten and lubricate your eyes.
Arrange Your Workstation:
 Every time you work, take time to adjust workstations that aren't quite right in
order to minimize awkward and frequently performed movements.
Adapt Laptops:
 Laptop computers are not ergonomically designed for prolonged use. The monitor
and keyboard are so close together that they cannot both be in good positions at
the same time. For prolonged use, it's best to add a separate monitor and
keyboard. The laptop can be planced on books so the top of the screen is at eye

level, then use an external keyboard so that your elbows can rest at 90° by your
side.
Modify Your Body Mechanics
 Do you wear eyeglasses? Make sure they fit properly to avoid tilting your head.
 Type with light strokes, and try to keep your muscles relaxed.
 Sit "tall," aligning your ears, shoulders and hips. When you sit, think about
making yourself an inch taller.
 Switch hands when using a mouse, if you are able.
 Completely rest your wrists during breaks, including taking your hands off the
mouse.
Adjust Your Work Patterns:
 Reduce prolonged computer time whenever possible.
 Break work into smaller segments and switch between tasks that use different
motions. For example, alternate use of mouse with reading and searching the web.
Move!
 Movement has many benefits: it relaxes tissues, lubricates joints and prevents
stiffness, improves circulation, reduces fatigue, and builds stamina. One study
showed that heavy computer users who successfully avoided computer-related
pain moved every 7 minutes.
 At least every 10 minutes, take a short (10-20 second) break. Take your hands off
the keyboard and move!
 Every 30-60 minutes, take a brief (2-5 minute) break to stretch and/or walk
around.
EXERCISE AT YOUR COMPUTER
Neck/Shoulders
 Neck Rotation: Slowly rotate your head as far as comfortable to the right, then
left.
 Shoulder Rotation: Circle your shoulders, then reverse directions.
 Head Side to Side: Bend your neck so left ear approaches left shoulder, then
repeat for right. Add a little resistance by pressing your hand against the side of
your head.
 Chin Tuck: Slide your chin inward, without bending your neck up or down. This
is easiest to practice initially against a wall. Tuck chin in, attempting to touch
back of neck to the wall while also maintaining head contact. Don't jam your chin
down to your chest.
 Shoulder Blade Retraction: Pull your shoulders down and back.
 Shrug: Slowly raise your shoulders toward ears and hold for a few seconds.
Gradually bring shoulders down and relax.
Back

 Shoulder Squeeze: Raise your arms in front of body, with elbows bent and thumbs
up. Pull elbows back, squeezing shoulder blades together. Hold for a few seconds
then release.
 Stretch Up: Sit up straight and imagine a cable attached to the top of your head.
Gradually stretch to be as tall as possible, hold for a few seconds, then relax.
Arms
 Arm Relaxation: Drop your arms and hands to your sides. Gently shake them for
a few seconds.
 Arm Rotation: Raise your arms in front of your body. Rotate arms so palms face
up, then rotate so backs of hands face each other.
Hands/Wrists
 Wrist Flex: With your elbows on desk, gently use left hand to bend right hand
back toward forearm. Hold for a few seconds, then relax. Repeat on other side.
 Finger Fan: Spread your fingers as far apart as possible, hold, then clench fists,
then release.
Feet
 Toe Curl: Flex toes up, then curl toes under. Release.
 Foot Rotation: Circle foot slowly from the ankle, then reverse.
Eyes
 Eye Rolls: Roll your eyes clockwise then counterclockwise briefly.
 Palm Eyes: Without touching your eyes, cup hands lightly over eyes for 30
seconds to rest them from light.
 Look Away: Exercise your eyes by periodically looking away from your
computer to focus on distant objects.

Keep fit:
 Physical fitness can help you avoid and treat problems related to computer use.
Build your stamina with exercises for strength, flexibility, and cardiovascular
health.
When to seek medical care: See a clinician if you experience:
 Constant pain
 Numbness
 Weakness
 Other problems that interfere with daily tasks
NECESSARY CONDITIONS FOR AN IDEAL COMPUTER ROOM ENVIRONMENT.
1. Cleanliness [books, manuals not encouraged] because they bring dust & caught fire
easily.
2. Air conditioners, which control the room and dehumidates it.
3. It should be dust free; dust is the biggest “killer” of hard drives.
4. No carpets, they caught fire more easily.

5. You are not allowed to eat, smoke or drink in the computer room.
6. No magnetic material should be in the computer room.
7. The computer room should be located in such a way that computers are not exposed
to direct sunlight or hot environments, use curtains if otherwise.
8. The computer room should be fitted with burglar bars, alarm systems, or guarded
24hours to ensure security.
9. The computer room should have surge protectors or suppressors to guard against
electrical faults and high voltages.
10. The computer room should have UPS [uninterrupted power supply] in case of power
failures, which may be fatal.
11. Computer room should be well ventilated, to allow for air circulation,
12. Foreign media, such as floppy diskettes, flash disks should not be allowed in order
to minimize virus spread.
13. Always switch off machines if not in use.
14. Avoid overloading circuits.
15. All cabling and wiring should not be exposed; it should be covered and should not
criss cross the room.
16. Leave enough space between computers and the walls.
17. Do not use chalk the computer room , dry wipe markers are encouraged.
HEALTH PROBLEMS ASSOCIATED WITH COMPUTER USE AND POSSIBLE
SOLUTIONS
1. BACK PROBLEMS
 Many computer users suffer serious back problems. This is probably due to a poor
posture or an awkward position while sitting at a computer.
Solutions
 A fully adjustable chair should avoid poor posture.
 Footrests can reduce these problems.
 Screens should tilt and turn to a position that avoids awkward movements.
2. EYE-STRAIN
 One health issue that can occur after using computers for a long time is eye-strain
(tiredness of the eyes).
This is caused by looking at a monitor which is a constant distance away. The muscles
that focus your eyes do not move, and so get tired and painful. Eye-strain can also cause
headaches.
Solutions
 Look away from the monitor at regular intervals – re-focus on distant or close objects
to exercise the muscles in the eye.
 Take regular breaks.
 Use an anti-glare filter in front of the monitor to cut down on screen reflections that can
also tire the eyes.
3. BACK AND NECK ACHE
 Many people suffer from back and neck pain after working at a computer for a long
time. This is usually due to them having a bad sitting posture.
Solutions
 Use an adjustable, ergonomic chair, and take the time to set it up properly.
 The computer keyboard and monitor should be at the correct height for the seated
person (keyboard lower than the elbow, top of monitor at eye level).

 Take regular breaks: get up, walk around, stretch your muscles
4. INJURY (RSI) IN WRISTS AND HANDS
 Any repetitive movement (same movement over and over again) can result in a health
problem called repetitive strain injury (RSI).
In particular, typing and using a mouse for long periods are common causes of RSI in
the wrist (it is often called carpal-tunnel syndrome).
Solutions
 Use a wrist-rest to support the wrists while typing and when using the mouse.
 Take regular breaks from typing or using the mouse.
5. OZONE IRRITATION
 Health experts have suggested that ozone emitted from laser printers can lead to
breathing problems.
Solution
 It is recommended that laser printers should be situated at least one metre away from
where people are sitting and there should be good ventilation in the area.
6. MUSCULOSKELETAL PROBLEMS:
 Muscle soreness and muscle fatigue are the most common complaints of regular
computer users. Back pain, chest pain, pain or numbness in arms, shoulder and feet top
the list. These types of problems mainly occur because your posture while using the
computer is not correct. Either you are sitting on an uncomfortable chair or your
workstation is not supportive of correct posture.
Solution
 Adjust your chair and desk such that your screen is either at your eye level or lower. Sit
with your back straight and legs perpendicular to the floor with feet resting flat on the
floor. Your elbows should rest at the sides.
 Take mini breaks from work and stretch a bit or go for a short walk.
7. HEADACHE
 Because of increased muscle tension or pain in the neck at the base of the skull, headache
is common problem with computer use. Many a times, prolonged use can affect eye
power which needs vision correction. This can also result in headache.
Solution
 Get your eye power tested if headache is a common problem with computer use. Keep
your neck straight when in front of the computer. Constantly looking down or stretching
the neck sideways can also cause pain. Take breaks in between and circle your neck a bit
to release the strain.
8. OBESITY
 Studies have shown that prolonged use of computers, especially in children, is the major
contributing factor of sedentary lifestyle and childhood obesity.
Solution
 Set limits for your children if they insist to playing computer games non-stop.
 Encourage your children to play outdoor games or to take up a hobby. Involve them in
extra-curricular activities
 Adults who work for 7-8 hours should avoid spending time on computer after reaching
home. Your body and mind both need to relax. Join a gym or go for evening jog and stay
physically active.
9. STRESS DISORDERS
 Technology has a huge impact on our behavior and emotions. Prolonged computer use
along with other factors like poor health, work pressure and job environment can make
you susceptible to stress. Moreover, the longer you uphold the stress, the more

susceptible you become to other health issues mentioned above. It can also lead to loss of
concentration, dizziness and weariness.
Solution
 Be proactive and take necessary measures to beat stress before it affects your health.
SPREADSHEET TERMINOLOGY
Microsoft Excel is a spreadsheet program written and distributed by Microsoft for
computers using the Microsoft Windows operating system and for Apple Macintosh
computers. It features an intuitive interface and capable calculation and graphing tools
which, along with aggressive marketing, have made Excel one of the most popular
microcomputer applications to date. ...
Absolute cell reference:
A cell address in a formula that does not change when copied
to another cell. An absolute reference has the form $A$1.
Active cell:
The selected cell in a worksheet. The active cell is surrounded
by a heavy border and is identified by the cell address.
Argument:
The information that a function uses to produce a new value or
perform an action. For example, a new value is displayed
when the SUM function adds the argument (A6:A12). An
argument consists of numbers, references, text, operators, or
error values.
Ascending:
A method of ordering a group of items from lowest to highest,
such as from A to Z.
AutoFilter:
Displays all records that meet the criteria as a subset of the
database.
AutoFormat:
A feature used to format a range of cells with a predefined set
of attributes.
AVERAGE function:
Sums the numbers in the specified range and then divides the
sum by the number of non-zero cells in the range.
Cell reference:
An unique address given to a cell; the coordinates of the
intersection of a column and a row.
Cell: Basic unit of a worksheet into which you enter data.
Chart:
A graphic representation of worksheet data. Values from
worksheet cells are displayed as bars, lines, or other shapes.
Common chart types are pie, bar, line, and area.

Column heading:
The lettered gray area at the top of each column that identifies
the letter of the column, such as column B.
Comment:
A note that explains, identifies, or comments on the
information in a specific cell or range of cells.
Condition:
Made up of two values and a relational operator, is true or
false for each cell in the range.
Conditional formatting:
Allows you to apply formatting that appears only when the
value in a cell meets conditions that you specify.
Criteria:
The conditions that control which records to display in a
query; the words or values used to determine the data that
appears in a data list.
Currency style format:
Displays a dollar sign to the left of the number, inserts a
comma every three positions to the left of the decimal point,
and displays numbers to the nearest cent (hundredths place).
Data table:
Range of cells that shows the answers generated by formulas
in which different values have been substituted.
Data validation:
Restricts the values that may be entered into a cell by the
worksheet user.
Debugging: Process of finding and correcting errors in the worksheet.
Descending:
A method of ordering a group of items from highest to lowest,
such as from Z to A.
Dummy data: Used in place of actual data to verify formulas in the template.
Embedded chart:
A chart that exists on a worksheet instead of on a separate
chart sheet.
Exploded Pie chart: A Pie chart with one or more slices offset.
Filter:
A set of criteria you can apply to records to show specific
tasks, records, or resources. The tasks, records, or resources
that match your criteria are listed or highlighted so that you
can focus on just the information you want.
Formula:
A sequence of values, cell references, names, functions, or
operators that produces a new value from existing values. A
formula always begins with an equal sign (=).

Function:
A built-in formula; a named and stored procedure that
performs a specific operation and returns a value.
Goal seeking:
Used if you know the result you want a formula to produce by
determining the value of a cell on which the formula depends.
Gridlines: The horizontal and vertical lines on the worksheet.
IF function:
A function that tests the content of the cell, performs a
calculation, and displays a value or text based on whether the
test is true or false.
Label: Row title or column title.
Legend: A box containing the name of each data series in a chart.
MAX function: Displays the highest value in a range.
MIN function: Displays the lowest value in a range.
NOW function: Used to enter the system date in a cell in the worksheet.
PivotChart:
An interactive chart that provides the user with ways to
graphically analyze data by varying the fields and categories
to present different views.
PivotTable:
An interactive worksheet table that summarizes data using a
selected format and calculations. It is called a pivot table
because you can rearrange the table structure around the data.
Protected cells: Cells that you cannot change.
Range:
Series of two or more adjacent cells in a column or row or a
rectangular group of cells.
Reference: A cell address used in a formula.
Relative cell reference:
In formulas, a reference to the address of another cell in
relation to a cell that contains a formula.
Template:
Special workbook or worksheet you can create and then use as
a pattern to create new, similar workbooks or worksheets.
Unprotected cells: Cells whose values you can change at any time.

Worksheet:
A set of rows, columns, and cells in which you store and
manipulate data. Several worksheets can appear in one
workbook, and you can switch among them easily by clicking
their tabs with the mouse.
X-axis:
A line, usually horizontal, along the bottom of a chart. The x-
axis shows the labels for the data series. Also called the
horizontal axis.
Y-axis:
A line, usually vertical, along the left side of a chart. The y-
axis shows the values for the data series.

ABBREVIATIONS
Here is a list of all common IT acronyms which is very useful nowadays for most
computer users as well as students!
A
 ADSL - Asymmetric Digital Subscriber Line
 AGP - Accelerated Graphics Port
 ALU - Arithmetic Logic Unit
 AMD - Advanced Micro Devices
 APC - American Power Conversion
 ASCII - American Standard Code for Information Interchange
 ARC net - Attached Resource Computer Network
B
 BIOS - Basic Input Output System
 BCD - Binary Coded Decimal
 BIOS - Basic Input/Output System
 BIS - Business Information System
 BIT - Binary Digit
 BLOG - Web Log
 BSYNC - Binary Synchronous Communications (protocol)
 BNC - Barrel Nut Connector
C
 C - C Programming Language
 CAD - Computer Aided Design
 CAL - Computer Aided Learning
 CASE - Computer Aided Software Engineering
 CDMA - Code Division Multiple Access
 CD-R - Compact Disk - Recordable
 CD-ROM - Compact Disk - Read Only Memory
 CD-RW - Compact Disk - Rewritable
 COBOL - Common Business-oriented Language (See HLL)
 CODEC - Coder/Decoder + Compression/Decompression
 COE- Common Operating Environment
 CPU - Central Processing Unit
 CRC - Cyclic Redundancy Check
 CRT - Cathode Ray Tube
 CSMA/CA- Carrier Sense Multiple Access/with Collision Avoidance
 CSMA/CD -Carrier Sense Multiple Access/with Collision Detection
 CD - Compact Disk
 CDR - Compact Disk Recorder
 CDRW - Compact Disk Re-Writer
 CD-ROM - Compact Disk - Read Only Memory
 CMOS - Complementary Metal Oxide Semiconductor
 CPU - Central Processing Unit
 CTX - CTX Technology Corporation (Commited to Excellence)
D
 DDR - Double Data Rate

 DDR-SDRAM - Double Data Rate - Synchronous Dynamic Random Access Memory
 DIMM - Dual Inline Memory Module
 DRAM - Dynamic Random Access Memory
 DPI - Dots Per Inch
 DSS - Decision Support System
 DTE - Data Terminal Equipment + Dumb Terminal Emulator
 DVD - Digital Video Disk
 DVD-A - Digital Video Disk-Audio
 DVD-AR - Digital Video Disk-Audio Recording
 DVD-R - Digital Video Disk-Recordable
 DVD-RAM - Digital Versatile Disc-RAM
 DVD-ROM - Digital Versatile Disc-ROM
 DVD-SR - Digital Video Disk-Stream Recording
 DVD-VR - Digital Video Disk-Video Recording
 DVR - Digital Video/Voice Recorder
 DVD - Digital Versatile Disc
 DVD-RAM - Digital Versatile Disk - Random Access Memory
E
 ECC - Error Correction Code
 EDO - Extended Data Out
 EEPROM - Electrically Erasable Programmable Read-Only Memory
 EPROM - Erasable Programmable Read-Only Memory
 EBCDIC - Extended Binary Coded Decimal Interchange Code [IBM]
 EEPROM - Electrically Erasable Programmable Read-Only Memory
 EFTS - Electronic Funds Transfer System
 E-MAIL - Electronic Mail
 EPROM - Electrically Programmable Read Only Memory +
 Erasable Programmable Read Only Memory
F
 FC-PGA - Flip Chip Pin Grid Array
 FDC - Floppy Disk Controller
 FDD - Floppy Disk Drive
 FPS - Frame Per Second
 FPU - Floating Point Unit
 FTP - File Transfer Protocol [Internet]
 FDDI - Fiber Digital Device Interface +
 Fiber Distributed Data Interface
 FDISK - Fixed Disk
 FDM - Frequency Division Multiplexing
 FDMA - Frequency Division Multiple Access
 FDX - Full Duplex
 FEC - Forward Error Correction
 FM - Frequency Modulation
 FORTRAN - Formula Translator (Programming Language)(See HLL)
 FTP - File Transfer Protocol
 FSB - Front Side Bus
G
 GB - Gigabytes
 GBps - Gigabytes per second or Gigabits per second
 GDI - Graphical Device Interface
 GHZ - Gigahertz

 GIGO - Garbage In, Garbage Out
 GIS - Geographic Information System
 GSM - Global System for Mobile-Communications (network)
 GUI - Graphical User Interface
 GHz - Gigahertz
H
 HDD - Hard Disk Drive
 HDD- Hard Disk Drive
 HDLC - High-Level Data Link Control
 HLL - HIGH LEVEL LANGUAGE
 HDTV - High Definition Television
 HTML - HyperText Markup Language
 HTTP - HyperText Transfer Protocol
 Hz - Hertz
 HP - Hewlett-Packard
 HSF - Heatsink-Fan
I
 IBM - International Business Machines Corporation
 IC - Integrated Circuit
 IDE - Integrated Drive Electronics
 IP - Internet Protocol
 IQL - Interactive Query Language
 ISDN - Integrated Services Digital Network
 IT - Information Technology
 LAN - Local Area Network
 LCD - Liquid Crystal Display
 LED - Light Emitting Diode
 LPT - Line Printer Terminal
 LPT1 - FirstParallelPrinterPort
 LPT2 - SecondParallelPrinterPort
 LPT3 - ThirdParallelPrinterPort
 IRQ - Interrupt Request
 ISA - Industry Standard Architecture
 ISO - International Standards Organization
J

K
 Kbps - Kilobits Per Second
 KBps - KiloBytes per second
L
 LG - LG Electronics
 LAN - Local Area Network
 LCD - Liquid Crystal Display
 LDT - Lightning Data Transport
 LED - Light Emitting Diode
M
 MAC - Media Access Control
 MB - MotherBoard or Megabyte
 MBps - Megabytes Per Second
 Mbps - Megabits Per Second or Megabits Per Second

 MHz - MegaHertz
 MIPS - Million Instructions Per Second
 MMX - Multi-Media Extensions
 MBps- Megabytes Per Second
 Mbps- Megabits Per Second
 MBR- Master Boot Record
 MHz- Megahertz
 MICR- Magnetic Ink Character Recognition
 MIDI- Musical Instrument Digital Interface
 MIS- Management Information System
 MODEM- Modulator/Demodulator
 MP3- MPEG Audio Layer 3
 MSAV- Microsoft Anti Virus [Microsoft]
 MS-DOS -Microsoft - Disk Operating System [Microsoft]
N
 NAS - Network Attached Storage
 NAT - Network Address Translation
 NIC - Network Interface Card
O
 OC - Overclock (Over Clock)
 OCZ - OCZ Technology
 OEM - Original Equipment Manufacturer
P
 PC - Personal Computer
 PCB - Printed Circuit Board
 PCI - Peripheral Component Interconnect
 PDA - Personal Digital Assistant
 PCMCIA - Peripheral Component Micro channel Interconnect Architecture
 PGA - Professional Graphics Array
 PLD - Programmable Logic Device
 PM - Private Message / Private Messaging
 PnP - Plug 'n Play
 POST - Power On Self Test
 PPPoA - Point-to-Point Protocol over ATM
 PPPoE - Point-to-Point Protocol over Ethernet
 PDF Package Definition File + Portable Document Format +
 Portable Document File + Processor Defined Function +
 Program Development Facility
 PDF Printer Description (file name extension)[Borland, Lotus]
 P2P Peer To Peer + People To People
 PSU - Power Supply Unit
R
 RAID - Redundant Array of Inexpensive Disks
 RAM - Random Access Memory
 RAMDAC - Random Access Memory Digital Analog Convertor
 RDRAM - Rambus Dynamic Random Access Memory
 ROM - Read Only Memory
 RPM - Revolutions Per Minute
S
 SCSI - Small Computer System Interface
 SDRAM - Synchronous Dynamic Random Access Memory

 SODIMM - Small Outline Dual Inline Memory Module
 SRAM - Static Random Access Memory
 Extensions
 SVGA - Super Video Graphics Array
T
 TB - Terabytes
 TBps - Terabytes per second
 Tbps - Terabits per second
U
 UART - Universal Asynchronous Receiver/Transmitter
 USB - Universal Serial Bus
 UTP - Unshieled Twisted Pair
V
 VCD - Video CD
 VPN - Virtual Private Network
W
 WAN - Wide Area Network
 WTB - Want to Buy
 WYSIWYG - What You See Is What You Get
X
 XGA - Extended Graphics Array
 XMS - Extended Memory Specification
 XT - Extended Technology

PRACTICALS
1. WINDOWS OS
2. WORD PROCESSING
3. SPREADSHEET PACKAGE
4. DATABASE
5. PRESENTATION

Introduction To ICTs

More Related Content

What's hot

Similar to Introduction To ICTs

More from Makaha Rutendo

Recently uploaded

Introduction To ICTs