The document provides an introduction to computers including definitions, components, and uses. It defines a computer as an electronic device that can accept data as input, process the data, and produce information as output based on stored instructions. The key components are identified as the input devices, central processing unit, memory, output devices, and storage devices. Examples of input devices include keyboards, mice, and scanners, while monitors and printers are identified as common output devices. The document then discusses the various types of computers from microcomputers to mainframes and supercomputers as well as their characteristics and uses.

1. Introduction to Computers
By
Ms.A.Thamizhiniyal, M.C.A.,
M.Phil.,
Assistant Professor,
Bon Secours College for Women,
Thanjavur.
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What Is A Computer?
A computer is an electronic device, operating
under the control of instructions (software) stored
in its own memory unit, that can accept data
(input), manipulate data (process), and produce
information (output) from the processing.
Generally, the term is used to describe a collection
of devices that function together as a system.

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Devices that comprise a computer system
Printer
(output)
Monitor
(output)
Speaker
(output)
Scanner
(input)
Mouse
(input)
Keyboard
(input)
System unit
(processor, memory…)
Storage devices
(CD-RW, Floppy,
Hard disk, zip,…)

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What Does A Computer Do?
Computers can perform four general operations,
which comprise the information processing cycle.
 Input
 Process
 Output
 Storage

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What Do Computers Do?
 Input, Process, Output, & Store
data
Input Process Output
Store Data

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Data and Information
 All computer processing requires data, which is a
collection of raw facts, figures and symbols, such as
numbers, words, images, video and sound, given to the
computer during the input phase.
 Computers manipulate data to create information.
Information is data that is organized, meaningful, and
useful.
 During the output Phase, the information that has been
created is put into some form, such as a printed report.
 The information can also be put in computer storage for
future use.

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Why Is A Computer So Powerful?
 The ability to perform the information processing
cycle with amazing speed.
 Reliability (low failure rate).
 Accuracy.
 Ability to store huge amounts of data and
information.
 Ability to communicate with other computers.

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How Does a Computer Know
what to do?
 It must be given a detailed list of instructions,
called a compute program or software, that tells
it exactly what to do.
 Before processing a specific job, the computer
program corresponding to that job must be stored
in memory.
 Once the program is stored in memory the
compute can start the operation by executing the
program instructions one after the other.

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What Are The Primary
Components Of A Computer ?
 Input devices.
 Central Processing Unit
(containing the control
unit and the
arithmetic/logic unit).
 Memory.
 Output devices.
 Storage devices.

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Uses of Computer
PC at Home
Common uses for the computer within the home
 Computer games
 Working from Home
 Banking from Home
 Connecting to the Web

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Uses of Computer
Office Applications
Stock Control
 Stock control is ideal for automation and in many
companies it is now completely computerized. The stock
control system keeps track of the number of items in stock
and can automatically order replacement items when
required.
Accounts / Payroll
 In most large organizations the accounts are
maintained by a computerized system. Due to the
repetitive nature of accounts a computer system is ideally
suited to this task and accuracy is guaranteed.

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Uses of Computer
Automated Production Systems
Many car factories are almost completely automated and the cars
are assembled by computer-controlled robots. This automation is
becoming increasingly common throughout industry.
Design Systems
Many products are designed using CAD (Computer Aided
Design) programs to produce exact specifications and detailed
drawings on the computer before producing models of new
products.

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Uses of Computer
Computers in Daily Life
 Accounts
 Games
 Educational
 On-line banking
 Smart ID cards
 Supermarkets
 Working from home (Tele-working)
 Internet

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History of Computers

15. The Five Generations of
Computers
The Five Generations of
Computers

16. First generation computers
(1940-1956)
 The first computers used vacuum tubes
for circuitry and magnetic
drums for memory.
 They were often enormous and taking
up entire room.
 First generation computers relied
on machine language.
 . They were very expensive to operate
and in addition to using a great deal of

17. First generation computers

18. Second generation computers
(1956-1963)
• Transistors replaced vacuum tubes and ushered in the
second generation of computers.
• Second-generation computers moved from
cryptic binary machine language to symbolic.
• High-level programming languages were also being
developed at this time, such as early versions of COBOL
and FORTRAN.
• These were also the first computers that stored their
instructions in their memory.

19. Second generation computers

20. Third generation computers
(1964-1971)
 The development of the integrated circuit was the hallmark
of the third generation of computers.
 Transistors were miniaturized and placed on siliconchips,
called semiconductors.
 Instead of punched cards and printouts, users interacted
with third generation computers through keyboards
and monitors and interfaced with an operating system.
 Allowed the device to run many different applications at
one time.

21. Third generation computers

22. Fourth generation computers
(1971-present)
 The microprocessor brought the fourth generation
of computers, as thousands of integrated circuits
were built onto a single silicon chip.
 The Intel 4004 chip, developed in 1971, located all
the components of the computer.
 From the central processing unit and memory to
input/output controls—on a single chip.
 . Fourth generation computers also saw the
development of GUIs, the mouse and
handheld devices.

23. Fourth generation computers

24. Fifth generation computers
(present and beyond)
 Fifth generation computing devices, based on artificial
intelligence.
 Are still in development, though there are some
applications, such as voice recognition.
 The use of parallel processing and superconductors is
helping to make artificial intelligence a reality.
 The goal of fifth-generation computing is to develop
devices that respond to natural language input and are
capable of learning and self-organization.

25. Fifth generation computers

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Types of Computers
Types of Computers
Microcomputer Minicomputer Mainframe Supercomputer

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Microcomputer
 Can be classified into:
 Desktop PCs

sits on desks, rarely moved, large and bulky.

Memory capacity, graphics capacity and software
availability vary from one computer to another Used
both for business and home applications

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Microcomputer
 Portable PCs

Can be moved easily from place to place

Weight may varies

Small PCs are popular known as laptop

Widely used by students, scientist, reporters, etc

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Microcomputer Model
Desktop NotebookLaptop
SubnotebookSubnotebook PalmtopPalmtop

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Microcomputer
 Advantages
 Small size
 Low cost
 Portability
 Low Computing Power
 Commonly used for personal applications
 Disadvantages
 Low processing speed

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Uses of Microcomputer
 Word Processing
 Home entertainment
 Home banking
 Printing
 Surfing the internet
 etc

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Minicomputer
 Medium sized computer
 Also called the minis
 e.g. IBM36, HP9000, etc
 Computing power lies between
microcomputer and mainframe computer

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MiniComputer
 Characteristics
 Bigger size than PCs
 Expensive than PCs
 Multi-User
 Difficult to use
 More computing power than PCs
 Used by medium sized business organizations,
colleges, libraries and banks.

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Uses of Minicomputer
 Control of Automated Teller Machine
(ATMs)
 Payroll
 Hospital patients registration
 Inventory Control for supermarket
 Insurance claims processing
 Small bank accounting and customer details
tracking

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Minicomputer
 Advantage
 Cater to multiple users
 Lower costs than mainframes
 Disadvantage
 Large
 Bulky

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Mainframe
 Known as enterprise
servers
 Occupies entire rooms or
floors
 Used for centralized
computing
 Serve distributed users and
small servers in a computing
network

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Main Frame
 Large, fast and expensive computer
 Cost millions of dollar
 e.g. IBM3091, ICL39, etc
 Characteristics:
 Bigger in size than minicomputers
 Very expensive
 Support a few hundred users simultaneously (Multi-Users)
 Difficult to use
 More computing power than minicomputers
 Have to be kept in a special air-conditioned room
 Used in big business organizations and government departments

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Mainframe
 Advantage
 Supports many users and instructions
 Large memory
 Disadvantage
 Huge size
 Expensive

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Supercomputer
 Fastest and expensive
 Used by applications for
molecular chemistry, nuclear
research, weather reports, and
advanced physics
 Consists of several computers
that work in parallel as a single
system

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Super Computer
 Advantage
 Speed
 Disadvantage
 Generate a large amount of
heat during operation

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Computer System
A computer system consists of three primary
units:
Input units – accept data
Processor unit – processes data by performing
comparisons and calculations
Output units – present the results

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COMPUTER SYSTEM
KEYBOARD
PROCESSOR
MONITOR
PRINTER
Storage
devices

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Input Devices
Data are facts, numbers and characters that are
entered into the computer via keyboard.
Other types of input devices are mouse, joystick,
light pens, scanners, camera, etc.

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Computer Input DevicesComputer Input Devices
 Keyboard
 Mouse/Trackball
 Joystick
 Light pen
 Pointing Stick
 Touchpad
 Touch screen
 Bar code reader
 Scanner
 Microphone
 Graphics Tablet
 Digital Cameras

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Processor Unit
Two main parts:
CPU – where the actual processing takes
place; and
Main memory – where data are stored.
The contents of main memory can be
transferred to auxiliary storage devices such as
hard disks, floppy diskettes, zip disks, compact
disks, or USB flash disk.

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 The microprocessor, the brains of the
computer. Referred to a CPU or processor
 Housed on a tiny silicon chip
 Chip contains millions of switches and
pathways that help your computer make
important decisions.
Central Processing UnitCentral Processing Unit

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•CPU knows which switches to turn on and
which to turn off because it receives its
instructions from computer programs
(software).
•CPU has two primary sections:
• Arithmetic/logic unit
• Control unit

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Arithmetic/logic unit (ALU):Arithmetic/logic unit (ALU):
- Performs arithmetic computations and logical
operations; by combining these two operations
the ALU can execute complex tasks.
- Arithmetic operations include addition,
subtractions, multiplication, and division.
- Logical operations involve comparisons.

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Control UnitControl Unit:
•Uses programming instructions, it controls
the flow of information through the processor
by controlling what happens inside the
processor.
•We communicate with the computer through
programming languages.
Examples: COBOL, C++, HTML,
Java Script or VisualBasic.net

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MemoryMemory
Found on the motherboard
 Short term
Random Access Memory (RAM)Random Access Memory (RAM)
 Long term
Read Only Memory (ROM)Read Only Memory (ROM)

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Random Access Memory (RAM)Random Access Memory (RAM)
•Memory on the motherboard that is short
term; where data, information, and program
instructions are stored temporarily on a RAM
chip or a set of RAM chips.
•Known as the main memory.
•This memory is considered volatile.
•The computer can read from and write to
RAM.

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•When the computer is turned off or if
there is loss of power, what ever is stored
in RAM disappears.
•“Temporary Memory” – Short Term

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Read-Only Memory (ROM)Read-Only Memory (ROM)
•Memory on the motherboard that is
long term; where the specific
instructions that are needed for the
computer to operate are stored.
•This memory is nonvolatile and your
computer can only read from a ROM
chip.

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•The instructions remain on the chip
regardless if the power is turned on or
off.
•Most common is the BIOS ROM; where
the computer uses instructions contained
on this chip to boot or start the system
when you turn on your computer.
•“Permanent Memory” – Long Term

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Output Unit
After the data has been
processed, the results are output in
the form of useful information.
Output units such as monitors
and printers make the result
accessible for use by people.

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Computer Output DevicesComputer Output Devices
MonitorMonitor: screen that display
information such as text,
numbers, and pictures-
softcopy.
PrinterPrinter: gives you
information from the
computer in printed form –
hardcopy.
SpeakersSpeakers: allow you
to hear voice, music,
and other sounds
from your computer.
ModemModem: allows you to
use your computer to
communicate with
other computers.

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Input Devices
 Keyboard.
 Mouse.

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