Introduction_to_Computers_Computer_Science.pptx

What is a Computer?
• Computers are everywhere!
• No matter how you perceive the impacts of computers, the statement is
true! Isn’t it?
• In the past two decades, computers have reshaped our lives at home, work,
school.
• Now we cannot imagine our daily life without the service of computers
directly or indirectly.
2

What is a Computer?
• The word computer comes from the word “compute” which means, “to
calculate”.
• A computer is an electronic device that processes, retrieves and stores data
according to a set of instructions.
• Thereby, a computer is an electronic device that can perform arithmetic
operations at high speed.
• A computer is also called a data processor because it can store, process,
and retrieve data whenever desired.
• Computer takes raw data as input from the user and gives us information
by processing these data using a set of instructions (usually program).
3

Evolution of Computers
• Computer was not invented in a day or by one!
• Blaise Pascal invented the first mechanical adding machine in 1642.
• Baron Gottfried Wilhelm von Leibniz invented the first calculator for
multiplication in 1671.
• Keyboard machines originated in the United States around 1880.
• Around 1880, Herman Hollerith came up with the concept of punched cards
that were extensively used as input media until late 1970s.
4

Evolution of Computers
• Charles Babbage is considered to be the father of modern digital computers
 He designed “Difference Engine” in 1822.
 He designed a fully automatic analytical engine in 1842 for performing
basic arithmetic functions.
 His efforts established a number of principles that are fundamental to
the design of any digital computer.
5

Some Well Known Early Computers
• The Mark I Computer (1937-44)
• The Atanasoff-Berry Computer (1939-42)
• The ENIAC (1943-46)
• The EDVAC (1946-52)
• The EDSAC (1947-49)
• Manchester Mark I (1948)
• The UNIVAC I (1951)
6

Computer Generations
• “Generation” in computer talk is a step in technology. It provides a
framework for the growth of computer industry.
• Originally it was used to distinguish between various hardware
technologies, but now it has been extended to include both hardware and
software.
• Till today, there are five computer generations.
7

Computer Generations: First and Second
8

Computer Generations: Fourth
10

Computer Generations: Fifth
11

Devices Used in Different Generations
12

Types of Computer
• Desktop computers
• Workstations
• Supercomputer
• Mainframe computer
• Notebook computers
• Micro computers
13

Capabilities of a Computer
• Automatic: Given a job, computer can work on it automatically without
human interventions.
• Speed: Computer can perform data processing jobs very fast, usually
measured in microseconds (10-6), nanoseconds (10-9), and picoseconds
(10-12).
• Accuracy: Accuracy of a computer is consistently high. Computer errors
caused due to incorrect input data or unreliable programs are often referred
to as GIGO.
• Diligence: Computer is free from monotony, tiredness, and lack of
concentration. It can continuously work for hours without creating any error
and without grumbling.
14

Capabilities of a Computer
• Versatility: Computer is capable of performing almost any task, if the task
can be reduced to a finite logical steps.
• Power of Remembering: Computer can store and recall any amount of
information because of its secondary storage capability.
15

Limitations of a Computer
• Lack of Creativity and Intuition: Computers operate based on predefined
algorithms and instructions. They lack the creativity, intuition, and
understanding that humans possess.
• No Common Sense: Computers process information strictly based on their
programmed logic and data, without the ability to make judgments.
• Energy Consumption: computers consume a significant amount of energy,
causing to environmental concerns.
• Processing Speed Limitations: Despite their remarkable processing
speeds, computers can still face limitations when dealing with extremely
complex calculations or simulations.
• Security Vulnerabilities: Computers are susceptible to various forms of
cyberattacks, viruses, malware, and hacking.
16

Limitations of a Computer
• Ethical and Moral Decision Making: Computers cannot make ethical or
moral decisions on their own. Any decision it perform is based on the
algorithms and data provided to it.
17

Parts of a Computer System
• A complete computer system consists of four parts-
 Hardware
 Software
 Data
 User
18

Computer Hardware
• The mechanical devices that make up the computer are called hardware
(any part of a computer that we can touch).
• A computer’s hardware devices fall into four categories-
 Processor
 Memory
 Input and output
 Storage
19

Processing Devices: Processor
• The main part of the CPU.
• The processor organizes and carries out instructions that come from either
the user or the software.
• Generally in a PC the processor usually consists of one or more specialized
chips called microprocessors.
20

Central Processing Unit (CPU)
• CPU is the central processing unit which performs five basic operations of a
computer system i.e., inputting, storing, processing, outputting and
controlling.
• It is the brain of a computer system
• It is responsible for controlling the operations of all other units of a computer
system.
• CPU consists of Arithmetic Logic Unit (ALU) and Control Unit (CU).
21
Arithmetic Logic Unit
(ALU)
Control Unit (CU)
Central Processing
Unit (CPU)

CPU - Basic Operations of a Computer
• Inputting: The process of entering data and instructions into the computer
system.
• Storing: Saving data and instructions to make them readily available for
initial or additional processing whenever required
• Processing: Performing arithmetic operations (add, subtract, multiply,
divide, etc.) or logical operations (comparisons like equal to, less than,
greater than, etc.) on data to convert them into useful information.
• Outputting: The process of producing useful information or results for the
user such as a printed report or visual display.
• Controlling: Directing the manner and sequence in which all of the above
operations are performed.
22

• Arithmetic Logic Unit of a computer system is the place where the actual
executions of instructions takes place during processing operation.
• Ex- performs mathematical, logical, and decision operations.
• Control Unit of a computer system manages and coordinates the operations
of all other components of the computer system.
• Ex - directs all the processors operations.
23

24

The BUS
• A bus is a path between the components of a computer.
• System Bus: The system bus connects the CPU to main memory (RAM)
and other primary components such as the Northbridge chip. It carries data,
addresses, and control signals.
• Expansion Bus: The expansion bus connects peripheral devices to the
CPU and main memory via expansion slots or connectors on the
motherboard. Examples include PCI, PCIe, and AGP buses.
• Internal Bus: The internal busconnects the CPU to cache memory and is
used for high-speed data transfer between the CPU and cache. The system
bus resides on the motherboard and connects the CPU to other devices.
25

The Data BUS
• The data bus is an electronic path that connects the CPU, memory, and the
other hardware devices on the motherboard.
• Actually, the bus is group of parallel wires.
• The number of wires in the bus affected the speed at which data can
transfer.
• But the bus speed is directly tied with CPU speed.
26

The Address and Control BUS
• The address bus is a set of wires similar to the data bus but the address
bus connects only the CPU and RAM and carries only memory addresses.
• The width of the address bus determines the maximum amount of memory
that can be addressed by the CPU.
• For example, a 32-bit address bus can address up to memory locations (4
GB of memory), while a 64-bit address bus can address a much larger
memory space.
• Control bus is used by the CPU to communicate with devices that are
contained within the computer.
• This occurs through physical connections such as cables or printed circuits.
27

Memory Devices: RAM/ROM/HDD
• Computer memory is one or more sets of chips that store data and/or
program instructions, either temporarily or permanently.
• Two most important types of memory are-
 Main/Primary memory
 Secondary memory
28

Memory Types: Main Memory
• Main memory is a fast type of computer memory which temporarily stores
all the information our PC needs right now and in the near future.
• It’s where our computer loads up all the things it thinks it will need to find
out soon, so that when it does need something, it can read it super fast.
• Ex - RAM and ROM.
29

Main Memory: RAM
• Random Access Memory (RAM)
 on silicon chips
 100 nano-second access time
 usually volatile (lose information if power turned off)
 data transferred at around 100 Mbytes/sec
• RAM has a tremendous impact on the speed and power of a computer.
30

Main Memory: ROM
• Read Only Memory (ROM)
 Usually nonvolatile that is ROM retains data without power, holding
permanent instructions.
 Quick data retrieval, measured in microseconds.
 It stores unchangeable firmware for system basics.
 ROM can be integrated directly onto silicon chips.
• ROMs are mainly used to store data, which do not change and are
frequently used. For example, system boot program.
31

PROM (Programmable Read-Only Memory)
• PROM is a type of memory chip that is programmed at the time of
manufacturing and retains its contents even when the power is turned off.
• PROM cells are initially programmed using a special device called a PROM
programmer.
• PROM is commonly used in various electronic devices for storing firmware,
boot loaders, and configuration data.
32

EPROM (Erasable Programmable Read-Only Memory)
• EPROM is a type of memory chip that can be programmed and erased
multiple times using ultraviolet (UV) light.
• EPROM cells are programmed by applying high voltages to the control
gates of the memory transistors.
• To erase data, the EPROM chip is exposed to UV light through the quartz
window, resetting all memory cells to their original state.
• EPROM is used in various applications where data needs to be
reprogrammed periodically, such as firmware development, BIOS updates,
and microcontroller programming.
33

EEPROM (Electrically Erasable Programmable Read-
Only Memory)
• EEPROM is a type of non-volatile memory that can be programmed and
erased electrically, offering flexibility and reusability.
• EEPROM cells are programmed by applying electrical signals to specific
memory locations, altering the charge stored in the memory cells.
• Unlike EPROM, EEPROM does not require UV light for erasure; instead, it
can be erased electrically using specific voltage levels.
• EEPROM is widely used in applications requiring non-volatile memory
storage that can be reprogrammed multiple times, such as firmware
storage, parameter storage, and data logging.
34

Memory Types: Secondary Memory
• Secondary memory is computer memory that is non-volatile and persistent
in nature and is not directly accessed by a computer/processor.
• It allows a user to store data that may be instantly and easily retrieved,
transported and used by applications and services.
• Secondary memory is also known as secondary storage.
• Ex- SSD, Magnetic Disk(HDD).
35

Secondary Memory: Various Dive/Disks
• Magnetic Disks
 Floppy Disks store around 1.4 Mbytes
 Hard Disks typically 40 Gigabytes to 100s of Gigabytes
 access time ~10ms, transfer rate 100kbytes/s
• Optical Disks
 use lasers to read and sometimes write
 more robust that magnetic media
 CD-ROM and DVD.
36

Core Memory
• Core memory, also known as magnetic core memory, was a type of random-
access memory (RAM) used in early computer systems from the 1950s to
the 1970s.
• Core memory consists of small magnetic cores woven into a grid of wires,
where each core represents one bit of data.
• Data is stored in core memory by magnetizing or demagnetizing individual
cores using electrical currents.
• Reading data involves sensing the magnetization state of the cores through
the wires.
• Core memory is non-volatile and retains data even when power is turned
off.
37

Bubble Memory
• Bubble memory is a type of non-volatile computer memory that uses a thin
film of magnetic material to store data.
• Developed in the 1970s, bubble memory was seen as a potential
replacement for disk drives and solid-state memory due to its durability and
non-volatile nature.
• Bubble memory stores data in magnetic bubbles that move along a thin film
of magnetic material.
• Data is written by creating and manipulating these magnetic bubbles using
electromagnetic fields.
• Bubbles can be moved, merged, and split to represent binary data.
38

Memory Management
• Memory management involves organizing and controlling computer memory
to optimize performance and resource utilization.
• Importance of memory management in ensuring efficient program execution
and system stability.
Overview of different types of memory:
• RAM (Random Access Memory): Volatile memory used for temporary
data storage during program execution.
• ROM (Read-Only Memory): Non-volatile memory containing firmware and
essential system instructions.
• Virtual Memory: Expansion of physical memory using disk storage to
accommodate larger programs and data sets.
39

Memory Management: Virtual Memory
Problem
• running lots of programs + each program large
• not enough RAM
Solution - Virtual memory
• store some programs temporarily on disk
• makes RAM appear bigger
But … swapping
• program on disk needs to run again
• copied from disk to RAM
• slows things down 40

Bulk Storage
• Bulk storage refers to the large-scale storage of data, typically in the
terabytes (TB), petabytes (PB), or exabytes (EB) range.
• It is used to store massive amounts of data that may not need frequent
access but require long-term retention.
Characteristics of Bulk Storage
• Massive Capacity
• Cost-Effectiveness.
• Slower Access Speed
41

Computer Hardware: Input Devices
• Input devices accept data and instructions from the user or from another
computer system.
• Ex-
 Keyboard, Mouse, microphone
 Trackball, Touchscreen, Joystick
 Scanner, Digital camera
 Digital Pen, Barcode reader etc.,
42

Computer Hardware: Input Devices
• Most common text input device
• Allows rapid entry of text by experienced users
• Keypress closes connection, causing a character code to be sent
• Usually connected by cable, but can be wireless
• layout – QWERTY
 Standardized layout
43

Computer Hardware: Output Devices
• Input devices return processed data to the user or to another computer
system.
• Ex-
 Monitor, Printer
 Speaker, Projector
 Sound system etc.
• Both input and output devices
 Communication devices e.g. modem
44

Scanners
• Take paper and convert it into a bitmap
• Two sorts of scanner
 flat-bed: paper placed on a glass plate, whole page converted into
bitmap
 hand-held: scanner passed over paper, digitizing strip typically 3-4”
wide
• Used in
 desktop publishing for incorporating photographs and other images.
 document storage and retrieval systems, doing away with paper
storage.
 special scanners for slides and photographic negatives. 45

Optical Mark Recognition
• OMR is a technology used to capture human-marked data from documents
such as surveys, tests, and questionnaires.
• It relies on special marks made by respondents that are interpreted by
scanning devices.
• Respondents mark predefined areas on paper documents using pencils,
pens, or markers.
• Specialized OMR scanners or machines capture the document images.
• Optical sensors detect the presence or absence of marks in designated
areas.
46

Ports and Overview of Common Ports
• Interfaces on a computer or device that enable connection with external
devices or peripherals.
• USB (Universal Serial Bus): Widely used for connecting peripherals such
as keyboards, mice, printers, and external storage devices.
• HDMI (High-Definition Multimedia Interface): Transmits audio and video
signals between devices, commonly used for connecting displays and TVs.
• Ethernet: Enables wired network connections for high-speed data transfer
and internet connectivity.
• Audio Jacks: Used for connecting speakers, headphones, microphones,
and other audio devices.
• Thunderbolt: Provides high-speed data transfer and power delivery,
commonly found in high-end computers and peripherals. 47

Peripherals and Common Peri. Devices
• External devices connected to a computer or device via ports to extend
functionality and provide additional features.
• Input Devices: Examples include keyboards, mice, trackpads,
touchscreens, and styluses used to input data into computers and devices.
• Output Devices: Include monitors, printers, speakers, projectors, and
headphones that display or output information from computers and devices.
• Storage Devices: External hard drives, USB flash drives, memory cards,
and optical drives used to store and retrieve data.
• Communication Devices: Modems, network adapters, and wireless
adapters facilitate communication and network connectivity.
48

Serial Communication
• Transmission of data one bit at a time over a single communication channel.
• Data is sent sequentially, bit by bit, over a single communication channel.
• Uses a single wire or channel for transmitting and receiving data.
• Common protocols include RS-232, UART, SPI, and I2C.
49

Serial Communication
Advantages
• Requires fewer wires compared to parallel communication, reducing
complexity and cost.
• Better suited for long-distance communication due to reduced signal
degradation.
Limitations
• Slower data transfer rates compared to parallel communication, especially
for large datasets.
• Transmitting data bit by bit can result in higher latency compared to parallel
transmission.
50

Parallel Communication
• Simultaneous transmission of multiple bits over multiple communication
channels.
• Data is sent simultaneously over multiple communication channels or wires.
• Each bit of data is transmitted over a separate wire, allowing for faster
transmission rates.
• Commonly used in older computer architectures and internal connections
within computer systems.
51

Parallel Communication
Advantages
• Allows for simultaneous transmission of multiple bits, resulting in higher
throughput.
• Data is transmitted in parallel, reducing the time required for transmission.
Limitations
• Requires multiple wires or channels, leading to increased complexity, cost,
and susceptibility to signal interference.
• Adding more channels can lead to signal integrity issues and increased
complexity in routing and synchronization.
52

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