This document provides an introductory overview of computers, defining them as electronic devices used for storing and processing data, highlighting their characteristics, applications, limitations, and classifications. It outlines the evolution of computers through five generations, explaining the progression from vacuum tubes to microprocessors and the rise of artificial intelligence in the latest generation. Additionally, the document details various types of computers, their functionalities, and the essential elements of a computer system.

1. CHAPTER ONE
INTRODUCTION TO COMPUTER
Prepared by Kenbon A.
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2. Definition
An electronic device for storing and processing data, typically in binary
form, according to instructions given to it in a variable program.
It is a collection of hardware and software components.
Device or machine for making calculations or controlling operations that
are expressible in numerical and logical terms. But today’s computers not
only process numbers, they process texts, pictures, multimedia and so on.
Generally, Computer is an electronic device; operating under the control of
instructions stored in its own memory unit and that can accept data,
process data, produce output and store the results for future use.
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A COMPUTER is an
electronic device that
performs tasks based on
instructions given by the
user.

4. Characteristics of computers
Automatic: once a program is in the computer’s memory, it continues
without the need for human intervention until completion.
Speed: a computer is a very fast device.
A powerful computer is capable of performing billion (109
) simple
arithmetic operations per second.
Accuracy: The computer’s accuracy is consistently high.
Storage capacity: computers help to save space and economy by storing
very large amount of data.
Diligence: unlike human beings, a computer is free from boredom,
tiredness, lack of concentration.
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5. Versatility:
It is the capability of a computer to perform different kinds
of works with same accuracy and efficiency.
Power of remembering:
A computer can store and recall huge amount of
information because of its secondary storage capability.
No IQ: Intelligent Quotient is zero.
It works only within the limits of what it has been
instructed to do.
No feeling:
They have no feelings and no instincts because they are
machines.
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6. Application of computers
• Today, every company is now directly or
indirectly dependent on computers for
information processing.
Science: scientists have been using computers
to develop theories, to analysis, and test the data.
E.g. detail study of how earthquakes affect
buildings or population affect weather pattern,
satellite based application.
Medicine and health care: now doctors are
using computers right from diagnosing the
illness to monitoring a patient’s status during
complex surgery.
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7. Engineering (architectures): the architects and engineering
are extremely using computers in designing and drawings.
Entertainment: computers are used to control the images
and sounds.
Communication: E-mail or electronic mail is one of the
communication media in which computer is used.
Business application: There are various concerns for which
computer are used such as in business applications (like at
the sale counter) that requires immediate response from
computer.
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8. Banking: in the field of banking and insurance computers
are extensively used. People can use the ATM (Automatic
Teller Machine) services 24 hours of the day in order to
deposit and withdraw cash.
Industries: - it is used for designing products, assisting
labors, controlling the work of the machineries in factory
e.t.c.
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9. Limitation of computers
Computers are programmed by Humans
Computers are dependent on humans
No Emotions and No Feelings
No thinking
No self care
Lack of Decision Making
Retrieval of memory
Dependency on power/electricity
Not able to express ideas
No IQ
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10. Generation of computers
All modern computers can be categorized in to five
generation:-
 First generation
 Second generation
 Third generation
 Fourth generation
 Fifth generation
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11. First generation(1940s-1950s)
It uses vacuum tubes as main component
It is very big ,expensive & slow
It required extensive air condition
It generates large heat
It uses magnetic drums for memory
It uses punched cards and paper tape for input purpose.
Output was displayed on printouts.
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12. Second generation(1950s-1960s)
It uses Transistors replaced vacuum tubes
B/c of the transistors, the computer becomes smaller in size,
fast in speed & more reliable than 1st
generation.
It uses punched cards for input and printouts for output
It controls by Assembly programming language
Magnetic tape is introduced for store data
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13. Third generation(1960s-1970s)
Integrated circuits(IC) called chips are replaced to
transistor. IC is a collection transistor.
Because of IC, Computers became:-
Smaller in size & power requirement
Very fast & more reliable
Magnetic disk is replaced to magnetic tape storage
device.
It uses keyboard instead of punched cards.
It uses monitors instead of printout.
It uses operating system which allows the computer
to run many applications at one time with a central
program that monitored the memory.
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14. Fourth generation(1970s-present)
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It uses
Microprocessor
replaces Integrated
Circuit.
Thousands of
Integrated Circuits
are built onto a
single silicon Chip.
Cheaper in price More powerful
Efficient &reliable
It uses Graphical
user interface and
mouse.

15. Five Generation(present-future)
It uses an artificial
intelligence & interact with
the natural language
The main is to narrow the
gap between human being
and computer.
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Elements of Computer system
1. Hardware
2. Software
3. People
4. Data
5. Connectivity
6. Procedure

17. 1. HARDWARE=
is the physical
equipment that
you can feel and
touch.
- It includes the CPU, mouse, keyboard,
printer, speakers, microphone, and
monitor.
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2. SOFTWARE-
are programs or
instructions that a
computer must
follow to do its task.
- The purpose is to process data
into useful information for people

19. 3. PEOPLE
are the most
important element
of a computer
system.
-They use and operate the computer.
-People use computers for a variety
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20. 4. DATA
include texts and
numbers, sounds,
images, and video
that you input into
the computer for
processing.
-Raw data are normal inputs entered
into the computer.
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21. 5.CONNECTIVITY
means that a
computer must be
connected to other
computers especially
through the internet.
Using the internet, people can share
and access data and greatly expand ones
capability and reach.
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6.PROCEDURES
are the step by
step instructions to
follow when using
hardware, software
and data.
These are normally written in manuals of
hardware and software manufactures.

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Types of computers classifications
Computers can be classified according to purpose, data
handling, and functionality.
Classification of
computers
Based on Data handling
(processing)
Based on
Functionality, size,
cost and speed
Micro computer
Mini Computer
Mainframe Computer
Super Computer
Digital
Analog
Hybrid
Based on
Purpose
General
Specific

24. Computers classification according to purpose
1. General purpose
 These machines can be used for various applications, ranging from
scientific as well as business applications.
 Even though such computers are versatile, they generally lack in
speed and efficiency.
Computers that you use home and schools are general purpose
computers.
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25. 2. Specific purpose
Designed to handle a specific problem or to perform a
single specific task built into the machine.
They can be providing the result very quickly and
effectively.
These computers are used for airline reservation,
satellite tracking, and air traffic control.
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26. Classification of computers according to
the method of operation (data handling)
Computers are classified into three by the way they
process data:-
1. Analog computers
2. Digital computers
3. Hybrid computers
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27. Analog computers
Analog computers which are operate by measuring.
They deal with continues variable.
They do not compute directly with numbers, rather, they
operate by measuring physical magnitude such as pressure
temperature, voltage, current and etc.
 E.g. Thermometer, voltmeter, speedometer
Analog computer has very low or limited memory
It can store less amount of data
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28. Digital computers
They operate by counting rather than measuring.
They operate directly upon numbers (or digits) that represent
numbers, letters, or other special symbols.
Digital computer is a computing device in which data is represented
by discrete numerical quantities.
It is represented by discrete numerical states (0s and 1s)
 E.g. Personal Computers
They have very high accuracy and speed than analog one
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29. Hybrid Computers
The best features of analog and digital computers can be combined
into a single device to form a hybrid computer.
It processes the information by collecting input data with analog
method, converts it into digital quantities, processes the digital values
and converts the output from digital to analog form.
Example:
Gasoline station: fuel vending machine measure the amount of fuel
via analog and display the result in digital form.
Ultrasound machine
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30. CLASSIFICATIONS OF COMPUTERS
ACCORDING TO CAPACITY
MICROCOMPUTER
MINICOMPUTER
MAINFRAME COMPUTER
SUPERCOMPUTER
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MICRO COMPUTER
also known as Personal computer
used in homes, offices; for individual and corporate uses
single users, Usually stand-alone to other computers but generally used to carry out
processing for a single user
speed of processor is 5 – 20 MIPS(Million instructions per second)
storage capacity is 32 Mb – 256 Mb of primary storage
No unusual power required for environment considerations; may fit on top of a table or
desk
examples are desktop, notebook, laptop, palmtop, personal digital assistant (PDA),
information appliances, network computers, technical workstations

32. Microcomputer (often called personal computers or PCs
for short) are the smallest but most important and most
frequently used of computer particularly for end users.
Basically, they can be grouped into three:
a. Laptop
b. Palmtop
c. Desktop.
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33. MINICOMPUTER
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midrange computer
For use by companies needing storage and processing
requirements, for more computer power
Multiple users, less than 100 users
speed of processor is 25 – 100 MIPS
storage capacity is 32 Mb – 512 Mb of primary storage
Requires controlled environment; Occupies own floor space, like
the size of a file cabinet
examples are Network servers, web servers, multiple use systems

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MAINFRAME COMPUTER
large scale computer
for medium to large size business; Used by business and government to provide
centralized storage processing and management of data of large amount
Multiple users greater than or equal to 100 users
speed of processor is 440 – 4,500 MIPS; May have several processors
storage capacity is 50 Mb – several gigabytes of primary storage
Requires controlled environment; Requires full time operators; Housed in a
cabinet where peripherals are in separate cabinets
examples are Enterprise systems, transaction processors, super server

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SUPERCOMPUTER
Used to compute intensive tasks
Designed for large-scale complex and scientific applications
Multiple users
speed of processor is 4 – 10 times faster than mainframes, Several processors,
60 Billion – 3 Trillion , Fastest, most processing power
storage capacity is 8,000 Mb+ +
Requires controlled environment; Space needed may be the size of a car
examples are Scalable servers, and Cray Computer

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