Basics Of Computers | The Computer System

Introduction
Since the evolution of man, computing has come a long way. Computer devices were invented one after
the other according to the necessity of the prevalent times. Today, technology has invaded our lives like
never before.
Computers have changed the way of our working in every field of life, for e.g. our system of shopping and
the way we communicate has changed.
People who used to send letters have now resorted to E – Mails. Computers can do variety of tasks quickly
and accurately.
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What Is Computer?
A computer is a programmable electronic device. It takes data
through input devices it processes the data according to a sequence
of instructions provided in the form of a program.
The result is called Input and given through some Output Device.
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A Computer System
The salient features of a Computer System are:-
• Speed: The speed at which computer operates cannot be matched with the human brain. It can perform millions of tasks per second.
• Storage Capacity: Enormous amount of data can be stored or retrieved from the memory of the computer instantly and correctly.
• Accuracy: Computers have a very high degree of accuracy.
• Versatility: Computer can be used to perform a variety of jobs with perfection.
• Diligence: It is basically a machine. Therefore, it doesn’t get tired nor does it suffer from boredom. It has an amazing ability to perform any number of
operations without losing concentration.
• Automation: Once, appropriate instructions given, a computer will carry out the task till its completion.
• Security: Data can be kept secured by using passwords, etc. so that another people may not excess it.

Limitations Of Computers
Inspite of its many advantages, our friendly computer has limitations too.
• Zero IQ and no thinking power: The computer has no intelligence of its
own. Hence, it cannot make its own decisions. It needs instructions for
every step. In time of any unexpected results, it cannot take any
alternative action.
• Dependence on power: It is dependent on electricity or any other source
of power.
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Applications Of A Computer
• Home: We can maintain your daily home records, do home work, communicate or use it for relaxation and recreation purpose.
• Entertainment and Fun: Listen to your favourite songs, watch movies, send e-cards and what not! Playing computer games is one of the most
enjoyable activities for most people.
• Communication: Computers can be an effective tool for communication between people who are far away. E-mail or electronic mail can be used
to exchange letters, greeting cards or even photographs.
• Education and Learning: Computers have a great role to play in the field of education. Teachers can use it as an effective tool to create and
present lessons and lectures.
• Office Automation: Computers have become an integral part of every company or office today.
• E-commerce: People can buy, sell and advertise a range of products. Netbanking is another major application of E- commerce.
• Banking: Computers have revolutionised modern banking.
• Airline/Railway Reservations: It is so easy to get a seat reserved to any destination from any computerised railway reservation counter.
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A Computer is a programmable machine that
responds to a specitic set of instructions in a
well-defined manner. It can execute the list
of instructions called a Program.
The physical components of a computer that
you can see, touch and feel are called
hardware.
Software is a collection of computer programs,
procedures and documentation that perform
some task on a computer system using the
hardware.
Design Of Computer System

This refers to the process which is used by the computer system to
interpret the given data, processes it, output the information and
saves the information.
Example: To read an E – Mail:
IPO Cycle
9
Sign into your E –
Mail account.
Loading E – Mail
Account.
Reading E – Mail.
Output
Processing
Input

Basic Operations Of Computer
Inputting: It is the process of entering data and instructions into a computer system.
Storing: It is the process of saving instructions to make them readily available for initial or additional
processing as and when required.
Processing: It is the process of performing arithmetic or logical operations on the data to convert into
useful information.
Outputting: It is the process of showing the results of an operation on a screen or as a printed copy.
Controlling: It is the process of directing the sequence in which the above operations are performed the
working of the hardware.

The Input Unit
Any information or data given to the computer is called Input. The device using
which a computer takes input is called an Input Device.
The input devices commonly seen along with all computers are Keyboard and
Mouse. But, there are special input devices like the Magnetic Ink Character
Reader (MICR), Optical Character Reader (OCR), Joystick, etc.
Any input device takes input, converts it to binary form and then passes it on
to the CPU for processing.
This is because all digital computers can understand only binary data. Input
data can be both data or instructions.
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The Output Unit
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Any information or data sent to the user as a result from the computer is
called an Output. The device using which a computer sends output is called an
Output Device.
The output unit in a computer can consist of one or more output devices
attached to your computer.
The output devices normally seen along with computers are the Visual Display
Unit (VDU) and the Printer. There are output devices like the Plotters used for
specialised tasks.

The Storage Unit
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Data and instructions entered into a computer system through input units
have to be stored inside the computer before actual processing starts.
Similarly, results produced by a computer after processing have to be kept
somewhere inside the computer system before being passed on to an output
unit. Storage Unit of a computer system caters to these type of needs.
It provides space for storing data and instructions. Storage units of all
computers are comprised of two types of memories: Primary Memory and
Secondary Memory.

Primary & Secondary memory
PRIMARY MEMORY
• It is also called the Main Memory. The CPU
directly stores and retrieves information from
here.
• It consists of two types of memory
technologies i.e. RAM and ROM.
• RAM is Random Access Memory. It is the
read/write memory but is a temporary storage
area. It holds the data that is being processed
and also the intermediate results in the
working area.
• ROM stands for Read Only Memory and has
permanent information in it.
SECONDARY MEMORY
• The secondary memory is used to store large
amount of data and instructions permanently.
This is also called Backup Storage.
• The main memory of the computer is temporary
memory and has limited storage capacity.
• So data has to be stored separately in a
secondary back up device to keep it permanent.
• Floppy Disk, Hard Disk, CD-ROM, DVD-ROM, Pen
Drive etc, are the secondary storage devices.
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Central Processing Unit
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The CPU is the core of the computer system where all processing is done. The
CPU is also called the Brain Of Computer.
As, in a human body, the brain takes all major decisions and other parts of the
body function as directed by the brain.
Similarly, in a computer system all major calculations and comparisons take
place inside the CPU and the CPU is responsible for activating and controlling
the operations of other units of the computer system.
Control Unit (CU) and Arithmetic Logic Unit (ALU) are the parts of CPU.

Control Unit
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The Control Unit acts like the traffic police. Its main function is to control and
coordinate the flow of data and instructions between all the other parts of the
CPU.
Normally the first program instruction is moved into the control unit from the
primary memory. This is interpreted and appropriate signals are sent out to
execute the instruction.
This is done with each instruction till the end. Thus, this is a sort of manager
of all operations that take place within the system.
The main three factors that affect the computer's performance are CPU speed,
RAM size and the number of applications executing simultaneously.

Arithmatic Logic Unit
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ALU is responsible for doing all the arithmetic calculations and logical
comparisons. The data and instructions are sent from the input area of the
memory to the ALU. The processing takes place here and the results are sent
back to the memory again.
The CPU uses operators like +, -, *, / for arithmetic operations and gives
numeric results. Logical comparisons always result in a TRUE or FALSE value.
Comparisons are done using relational operators like <, <=, >, >=, =, =, <>.

Communication Technologies
Communication is the process of sending and receiving information. Computers and Internet have revolutionised the ways of communication. One can send
messages, pictures, videos and documents anywhere by connecting the computer with the Internet. Internet (International Computer Network) is a network
of computers. The local networks all over the world are linked to it by wires, telephone lines and satellites.
A Website is like a book that contains many pages called Webpages to provide different types of information. People educate themselves through the
Internet, take exams and even work online. Air and train tickets, hotel bookings and money transactions through e-banking are also done through the
Internet. Computers and Internet save time and increase efficiency.

E – Mails
E-mail is a system that allows messages to be sent and received by computers.
It is the most common form of electronic communication.
E-mail messages are text-based but other type of files can also be sent or
received as attachments.
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Video Conferencing
Video Conferencing is a system that allows face-to-face conversation with
different people who are sitting at different locations.
It involves people sitting in front of a Camera and a Microphone.
They can watch other people on a screen and listen to them through speakers.
Video Camera, Microphone, Monitor, Speakers, High Speed Internet Connection
are the things required for video conferencing.
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Smartphones
Smartphones allow people to be contactable when they are away from each other.
The people can work, even when out of the office. Smartphones can perform a
wide variety of tasks like :
• Make and receive telephone calls.
• Send and receive SMS(Short Message Service)/E-mails.
• Send and receive files such as images, text documents etc.
• Edit documents.
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Internet Telephony
Internet Telephony or VoIP is becoming very popular now-a-days. Instead of
using the normal telephone network, VoIP system sends voices through the
Internet, just like any other data.
Hence, VoIP systems use Internet connection to send and receive phone calls.
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Advantages Disadvantages
No telephone line is required Requires high-speed Internet connection
Call costs are very low Not very much reliable
Can include video Call quality depends on the speed of the
Internet connection

Satellite Communication System
A Satellite contains antennas, Transponders (to allow receiving and sending of data), Solar Panels (that store power from the Sun) and Propulsion (to ensure the
satellite is in the correct orbit at all times).The process of communication begins at an Earth Station.
The Earth Station is the installation designed to transmit and receive signals from the satellite that moves around the earth.
The Earth Station sends information in the form of high frequency signals to satellites that receive and retransmit the signals back to earth. These
retransmitted signals are then received by other Earth Stations in the coverage area of the satellite.
The transmission system from the Earth Station to the satellite is called Uplink and the transmission system from the satellite to the Earth Station is
called Downlink.
The satellite system is used to transmit data from one part of the planet to another. The satellite systems are used to transmit television, telephone and Internet
data around the globe.

Basics Of Computers | The Computer System

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Basics Of Computers | The Computer System