Shubharambha Computer book 5 layout for ctp 2074

New

Gateway to
Computer Science

A Complete Text Book of Computer Science

Authors : Dinesh Adhikari, Dilendra Bhatta

Contributing Co-authors : Laxman Adhikari, Shekhar Poudel
Toyaram Giri, Arjun Poudel

Layout Design : Zeeta Computer Service Pvt. Ltd.
(SaminR.Dhungana)Ghantaghar,

Kathmandu, Nepal

Copyright © : Publisher

Edition : 2075

Publication : Shubharambha Publication Pvt. Ltd.
Kathmandu, Nepal

Preface Contents

Along with the evolution of human Unit 1
beings new thoughts, area of knowledge
and technology also developed together. 1. Computer Introduction
Among the eruptions, ICT (Information
and Communication Technology) is 2. Generations of Computer 16
one which has unquestionably become
important part of human beings. A 3. Types of Computer 30
person is not better than a caged pigeon
if s/he is far from computer technology 4. Computer System 45
in this century. New Gateway to
Computer Science Book-5 is a 5.. Software of Computer 71
complete package which obviously
supports a lot to the students as this is 6. Working with Paint brush 81
one of the most useful Text Book, so
far available in the market. This book 7. Working with Word Pad 99
is completely prepared considering the
level of the students. This text has the 8. Introduction to Internet 120
various salient features like it focus on
child psychology, inclusion of comic’s List of Abbreviations 131
cartoons, conversation based, focus
on pictorial descriptions,quiz section, Quiz Section 133
worksheets, etc.
Model Question Paper 138
Comments and constructive suggestions
are highly welcomed from the readers
and professionals to update this text
book.

Suggest us:

[email protected]

Thank you.

Unit 1 Computer
Introduction

Expected Competency
At the end of this unit, students will be able to,
¬¬ define the computer.
¬¬ tell about the advantages and disadvantage of a computer.
¬¬ tell the characteristics of a computer.
¬¬ discuss about the working principle of a computer.
¬¬ discuss the application area of a computer.

Computer Introduction 1

Introduction

The role of computer in present day
is indescribable. Computers have
almost changed the world. Computers
have become the most essential and
inseparable tools of human life. Without
computer, people are unable to do their
daily activities. It is essential to have
a computer for individual. The literacy rate of the computer is
increasing nowadays. Here, the literacy means knowing about the
computers, understanding their utilities, knowing the way they
work, use and control. A computer is also an important tools for
communication.

The term computer is derived from the Latin term computare,
this means to calculate. A computer can work with the help of data
and instructions. The computer is an advance electronic machine
that logically and arithmetically works when a user inputs the
instructions.

Definition of computer

We can define the computer in various ways. Simply, the computer
is defined as a machine which computes the data. We can define
the computer as below.

A computer is an electronic device that manipulates information,
or data. It has the ability to store, retrieve, and process data.

A computer is an electronic device that can accept data, process
it according to a set of predefined instructions and then display
the meaningful output.

A computer is an electronic machine which is used for data
processing to produce meaningful information.

A computer is an electronic device which is used to store the data,
as per given instructions it gives results quickly and accurately.

2 New Gateway to Computer Science 5

Advantage of Computer

It is a highly accurate device even it works at a high
speed.

It has the capacity of storing large volume of data.
It can perform variety of tasks.
It is a reliable machine.
It is used to solve complex type of calculations.
It is one of the best tools for communication.

Disadvantage of Technology

It does not have its own decision making power.
It cannot work without human instructions.
It needs trained person to handle.
It creates unemployment problem.
It is impossible to display correct output if the input is

wrong.

Characteristics of computer

Computers have some important characteristics which are
presented below.

High Speed

The computer can perform complex calculations more easily
than humans. It means a computer can work at a very high speed.
The computer can perform millions (1,000,000) of instructions
within a very few seconds. The working speeds of computers are
measured as below.

Computer Introduction 3

Second (s) 1 × 10–­ 3 s 1/1000 sec.
Millisecond 1 × 10–­ 6 s 1/1,000,000 sec.
Microsecond 1 × 10–­ 9 s 1/1,000,000,000 sec.
Nanosecond 1 × 10–­ 12 s 1/1,000,000,000,000 sec.
Picosecond 1 × 10–­ 15 s 1/1,000,000,000,000,000 sec.
Femtosecond 1 × 10–­ 18 s 1/1,000,000,000,000,000,000 sec.
Attosecond

Accuracy

Once we give correct data and instructions, the computer can do
the work automatically. Computers are accurate machines. The
accuracy of a computer is very high. If the data and instructions
given are correct, the result displayed by the computer will also
be correct. A computer always provides accurate output when
the inputs are accurate. It can also be defined by the term GIGO
(Garbage in Garbage Out) which means wrong input provides
wrong output and correct input provides correct output.

Versatility

The computer is versatile(all-rounder) machine because it can be
used everywhere. We can use the computer to perform completely
different type of work at the same time. It has the features of
Multi-processing. It has a wide range of applications and is
used in different fields like education, science and technology,
business, medicines, research, etc.

4 New Gateway to Computer Science 5

Diligence

Computers never get tired or bored when the same task is
repeated many time. Efficiency, time of calculation, accuracy will
always remain the same. A computer is capable to do the task
again and again without losing its efficiency, speed and accuracy.
A computer never suffers from the tiredness and concentration
problem. It never feels lazy and bored to do the task.

Memory

A computer can store a large volume of data according to its storage
capacity. It stores the data which the user wants to retrieve for
future use. Some of the popular storage devices are Floppy disks,
Optical disks, Zip drives, etc. The following are some memory
measurement units of the storage devices.

Data Measurement Unit Size

Bit Single Binary Digit (1 or 0)

Byte 8 bits

Kilobyte (KB) 1,024 Bytes

Megabyte (MB) 1,024 Kilobytes

Gigabyte (GB) 1,024 Megabytes

Terabyte (TB) 1,024 Gigabytes

Petabyte (PB) 1,024 Terabytes

Exabyte (EB) 1,024 Petabytes

Computer Introduction 5

Quick Learn!

¬¬ The term computer is derived from the Latin term
computer, this means to calculate.

¬¬ A  computer  is an electronic device that manipulates
information, or data. It has the ability to store, retrieve,
and process data.

¬¬ A computer is a highly accurate device that it works at a
very high speed.

¬¬ High speed, accuracy, versatility, diligence, memory, etc.
are the features of a computer.

Oral Evaluation

yy Tell the definition of a computer.
yy Tell any three advantages and disadvantages of the computer.
yy Tell any four characteristics of the computer?
yy The computer is called a versatile machine, Why?
yy What are the different storage measurement units?

Basic Working principle of computer

A computer performs mainly four functions:
Receive input through the various input devices.
Process information to perform arithmetic or logical

operations.
Produce output with the help of output devices.
Store information on the storage devices.

6 New Gateway to Computer Science 5

Scanner Microprocessor Printer

Speaker

Camera

Mouse Keyboard Monitor

Input Processing Output

Input

Inputs are the raw data given to the computer
for processing. The computer accepts data
from the user with the help of input devices like
keyboard, mouse, light pen, microphone, etc.

Process

The computer processes the data when it gets
input from the user. The processing activity
of the computer is done by the Central
Processing Unit (CPU).

Output

The output is always meaningful. The output
devices of the computer like monitor, printer,
speaker, etc. can display the meaningful
information. The output devices can display
the output only after processing.

Computer Introduction 7

Storage

A storage device is any computer hardware
that is used for data storage in permanent or
in temporary form. When the result is final,
we can use storage devices to store the data
for the future use. There are some permanent
and temporary storages with the computer system. Generally, we
use the secondary storage devices to store the data permanently.

The application areas of computer

There is a great role of the computer technology for the latest
achievement. The knowledge and the uses of a computer are
essential for each and every person. Computers are helping
people in different ways. The use of a computer is increasing
day by day. Nowadays, people are massively using the computer
everywhere like at hospital, bank, departmental store, school and
colleges, entertainment, communication, etc. The following are
some application areas of the computer.

Computer in Education

Computers are commonly used in
school and college for teaching and
learning activities. A teacher can
make his teaching techniques easier
and interactive with the help of the
computer tools. Students can also use
the computer as their learning tools.
Students can search about various topics on the internet and
teachers also can take help of the internet and do lots of research
work so that he can collect lots of ideas and information about the
learning process. A teacher can prepare a slide and demonstrate
it in the class. Students also can do research work in their various
subjects that they require on it.

8 New Gateway to Computer Science 5

Computer in Bank

Computers are massively used in
bank these days. With the help of the
computers,we can keep the records
of customers; we can calculate the
money; check the balance, verify
the signature, deposit and withdraw
money, etc. Online banking, mobile
banking, ATM card, Electronic Fund
Transfer System (EFTS)are also available because of the use of
computer at bank.

Computer for entertainment

Entertainment is also an important
part of human life. Computers are used
for listening music, watching videos
and films, play games, online booking
of film tickets, downloading music and
videos, etc. So the computers play a
major role in the entertainment sector too.

Computer at hospital

Hospitals use computers to keep the
records of patients, doctors and staff.
These days, the computers are used
to keep and display the duty roster of
doctors also. The computers are used
to check the various internal organs of
human so that it is easy to find out the health problems. X-Ray ,
CT-Scan, test of heart, test of kidney, endoscopy, ultrasound, etc.
are possible to do within a second with the help of the computer.
So there is a great role of computer in the medical science.

Computer Introduction 9

Quick Learn!

Education

¬¬ It is used as a teaching learning tool.
¬¬ It is used for result processing.
¬¬ It is used to prepare bills.
¬¬ It is used to keep the records of teachers.

Health and Medicine

¬¬ Research in health.
¬¬ CT-Scanning and Ultra sound
¬¬ Record keeping of patients
¬¬ Performing the various clinical test

Banking

¬¬ To provide online and mobile banking facility
¬¬ To provide ATM facilities
¬¬ To check the balance
¬¬ To verify the signature.

Library

¬¬ To keep the records of books
¬¬ To check the stocks of books.
¬¬ To enter the issue date and return date of the books.

Oral Evaluation

yy Tell the basic working principle of a computer.
yy What are the application areas of a computer?
yy Explain the role of a computer in education.
yy What is an input?

yy For what purposes are computers used at hospitals?

10 New Gateway to Computer Science 5

Let's Revise

áá The term computer is derived from the Latin term
computare, this means to calculate.

áá A computer can work with the help of data and
instructions.

áá A computer is an advance electronic machine that
logically and arithmetically works when a user inputs
the instructions.

áá A computer is an electronic device that can accept data,
process it according to a set of predefined instructions
and then display the meaningful output.

áá A computer is a highly accurate device that works at a
very high speed.

áá Once we give the correct data and instructions, the
computer can do the work automatically.

áá The computer is a versatile machine because it can be
used everywhere.

áá Computers never get tired or bored when the same task
is repeated for multiple times.

áá Inputs are the raw data given to the computer for
processing.

áá The computer accepts data from the user with the help of
input devices.

áá The computer processes the data when it gets input from
the user.

áá The processing activity of a computer is done by the
Central Processing Unit (CPU) of the computer.

áá The output is always meaningful.
áá When the result is final, we can use storage devices of the

computer for the data storage.
áá Secondary memories are used to store data permanently.
áá Nowadays, the computers are commonly used in school

and college for teaching and learning activities.
áá A teacher can make teaching techniques easier and

interactive with the help of the computer tools.

Computer Introduction 11

Evaluation Time

1. Choose the best answer from the given alternatives.

a. What does a computer do?

i. Process data ii. Store data iii. both

b. Which of the following is the advantage of a computer?

i. It can store large volume of data.
ii. It creates unemployment.
iii. It does not have its decision making power.
c. Which of the following is a characteristic of the computer?

i. High speed ii. Versatile iii. Both

d. What do you mean by 0 or 1 character?

i. bit ii. Byte iii. Kilobyte

e. In which character of the computer does a GIGO fall?

i. Versatile ii. Storage iii. Accuracy
f. 1024 megabyte equals to:

i. 1 gigabyte ii. 2 gigabyte iii. 1 Kilobyte

g. Which of the following is the working principle of the
computer?

i. Input-Process-Output-Storage
ii. Output-Storage-Input
iii. Output-Input
h. For what purpose the computers are used at bank?

i. Signature verification

ii. X-Ray iii. CT-Scan

12 New Gateway to Computer Science 5

i. For what purpose are computers used in entertainment?

i. to listen music and watch movies.

ii. to keep the records of books.

iii. to check the bank balance.

j. Which of the following term is related to ‘meaningful
information’?

i. Process ii. Input iii. Output

2. Write ‘True’ for correct and ‘False’ for the wrong
one.

a. The term computer is derived from the Latin term
computer.

b. A computer is an electronic machine which is used for
data processing to produce meaningful information.

c. A computer cannot perform complex calculations more
easily than human.

d. A computer always provides accurate output even the
inputs are not accurate.

e. The computer is a versatile machine because it can be
used everywhere.

f. A computer cannot store large volume of data.

g. A computer accepts data from the user with the help of
the output devices like keyboard, mouse and light pen.

h. The output is always meaningless.

i. Online banking, mobile banking, ATM card, Electronic
Fund Transfer system are also available because of the
use of the computer at bank.

j. X-Ray , CT-Scan, test of heart, test of kidney, endoscopy,
ultrasound, etc. are possible to do within a second with
the help of a computer.

Computer Introduction 13

3. Fill in the blanks with suitable words.

a. A …………………. can work with the help of data and
instructions.

b. The computer is a highly accurate device even it works at
a …………… speed.

c. The computer is a …………………. machine because it can
be used everywhere.

d. ……………………… are the raw data given to the computer
for processing.

e. The computer accepts data from the user with the help
of ……………….. devices.

f. The computer …………………… the data when it gets input
from the user.

g. The processing activity of a computer is done by the
……………………………. of the computer.

h. When the result is final, we can use …………………….
devices of computer for the data storage.

i. …………………….. memories are used to store data
permanently.

j. Computers are used at ............... to keep the records of
patients, doctors and staff.

4. Write down the single technical term for the
following descriptions.

a. Once we give the correct data and instructions, the
computer can do the work itself.

b. The computer is all-rounder machine because it can be
used everywhere.

14 New Gateway to Computer Science 5

c. Computers never get tired or bored when the same task
is repeated for multiple times.

d. Raw data are given to the computer for processing.
e. The meaningful information can be displayed by the

output devices like monitor, printer, speaker, etc. at the
computer.
3. Answer the given questions.
a. Define computer. Mention at least two advantages and
disadvantages of the computer.
b. What are the characteristics of the computer? Explain
any two of them.
c. What are the main functions of a computer?
d. What is the working principle of the computer?
e. Write down various storage measurement units.
f. What are the application areas of the computer? List
them.
g. Explain the role of a computer in education.
h. Why are computers used at hospital? Explain in short.

Project Work

Draw a well labelled diagram of the computer to represent
the working principle of a computer.

Computer Introduction 15

Unit 2 Generations of
computer

Expected Competency

At the end of this unit, students will be able to,
¬¬ understand the various computer generations.
¬¬ discuss about the memory components of different

computer generations.
¬¬ tell the features of each generation of computer.

16 New Gateway to Computer Science 5

Introduction

The evolution of computer started from 16th century and took long
period of time to form the computer what we have today. The
present day computer has also undergone rapid change during
the last fifty years. The period, during which the evolution of
computer took place, can be divided into five distinct phases, on
the basis of the type of switching circuits known as the generations
of Computers. In this chapter we will learn about each of the five
generations of computers and the technology developments that
have led to the use of current devices that we use today.

First generations of computer (1946-1958)

The first generation computers IBM 650
were developed during 1946
to 1958 AD. These computers
used vacuum tubes (valves) as
major electronic component
which was developed by Lee

Generations of computer 17

Dee forest. The machine language was used for writing the
programs in these generations. These computers were used only
for scientific and engineering applications. The benefit of vacuum
tubes technology is that, it made the onset of Electronic digital
computer. Vacuum tubes were only electronic devices available
during those days which made computing possible.

Name of first generation computers:

The different computers were developed during this time like
ENIAC, EDSAC, UNIVAC-I, EDVAC, Mark I, IBM 701, IBM 650,
etc.

Features of the first generation computers

a. The size was extremely large.

b. Vacuum tubes were used as a memory component.

c. The operating system was very slow.

d. Machine languages were used for writing the programs.

e. It consumed a lot of power and produced more heat.

f. It was difficult to maintain.

Second Generation Computers (1959 – 1964 AD)

The second generation computers UNIVAC II
were developed during 1959 to
1964 AD. These computers used
transistors as major electronic
component which was developed
by John Bardeen, Walter Brattain
and William Shockley in 1947.
Transistors replaced the large
electric tubes used in the first

18 New Gateway to Computer Science 5

generation computer. Transistors are smaller than electric tubes
and have higher operating speed. They have no more wire and
require no heating. Manufacturing cost of them was also very
low. Thus the size of the computer got reduced significantly. The
assembly language and the high level language were developed
during these generations. These computers were used for business
applications.

Name of the second generation computers:

IBM 7070, IBM 1620, IBM 1401, UNIVAC II , MAKR III , CDC
1604 , ICL 1901 were developed during the second generations.

Features of the second generation computers

a. Transistors were used as a memory component.
b. They were smaller and reliable than the first generation

computers.
c. Magnetic cores for primary and magnetic tape for

secondary storage were used.
d. Assembly language and high level language were used.
e. They consumed less power and generated very less heat.

f. The operating speed was up to microsecond.

Quick Learn!

¬¬ Transistors were developed by John Bardeen, Walter
Brattain and William Shockley in 1947.

¬¬ Transistors are smaller than electric tubes and have
higher operating speed.

¬¬ The assembly language and the high level languages
were developed during second generations.

Generations of computer 19

Third Generation Computers (1965-1974 AD)

The third generation computers

were developed during 1965 to

1974 AD. These computers used

Integrated Circuit (IC) which

was developed by Jack Kilby.

The third generation computers

were introduced in 1964 but were

started to use form 1965 AD. The

ICs are popularly known as Chips. IBM 370
A single IC has many transistors,

registers and capacitors built on a single thin slice of silicon. So

it is quite smaller. Computers of this generation were small in

size, were of low cost, had large memory and processing speed

was very high. These computers were used for both scientific and

business purpose. Low level and high level language were used to

write the programs.

Name of the third generation computers:

IBM system/ 360, 370, GE 600 series, ICT 1900 series, VAX 11/
780, Honeywell 200, ICL 2800, Burroughs 5700 etc. computers
were popular during second generation.

Features of the third generation computers

Integrated Circuit was used as a memory component.

20 New Gateway to Computer Science 5

They used semiconductor device as a primary storage.
Mini computers were started to develop.
They were more flexible with input and output devices.
The operating speed was up to nanosecond.
More reliable, smaller, faster and less expensive than the

previous computers.

Quick Learn!

¬¬ Integrated Circuit (IC) was developed by Jack Kilby.
¬¬ The ICs are popularly known as Chips.
¬¬ A single IC has many transistors, registers and capacitors

built on a single thin slice of silicon.
¬¬ Low level and high level language were used to write the

programs on third generation computer.

Oral Evaluation

yy Tell about the computer generation.
yy What was the memory device of the first generation

computer?
yy Who was the inventor of the vacuum tube?
yy Tell any two features of the first generation computer.
yy Name some computers that were developed during the

third generation?
yy Who were the inventors of transistors?

Generations of computer 21

Fourth Generation computers (1975 – till date)

The present day computers that

we see are the fourth generation

computers. These computers

started to work from 1975 AD.

Microprocessor chip is the main

electronic component of these

computers which is developed by Apple/ Machintosh
Intel Corporation. Microprocessor

chip is the combination of LSIC (Large Scale Integrated Circuits)

and VLSIC (Very Large Scale Integrated Circuits). Due to the

development of microprocessor, it is possible to place computer’s

central processing unit (CPU) on single chip. These computers

are called microcomputers. The personal computer (PC) that we

have seen these days is the Fourth Generation Computer. The

first microprocessor was developed by Intel Corporation of the

USA in 1971.

Name of the fourth generation computers:

IBM 3033, HP 3000, Apple/ Macintosh, DEC 10, Super brain,
Cray X-MP, IBM PC,INTEL 8086, 80286, Pentium, etc. are the
fourth generation computers.

Features of the fourth generation computers

Microprocessors are used as a memory component.
It has a large storage capacity and faster processing speed.
The operating speed started to measure in nanosecond.

22 New Gateway to Computer Science 5

It can easily understand high level language.
The size is reduced to desktop, laptop and palmtop.
Many input and output devices are used.

Quick Learn!

¬¬ Microprocessor chip is developed by Intel Corporation.
¬¬ Marcian"Ted" Hoff is one of the inventors of the

microprocessor.
¬¬ Microprocessors also control the logic of almost

all digital devices,
¬¬ The first microprocessor was the Intel 4004, introduced

in 1971. 

Fifth Generation computer (1991 – incomplete)

The fifth generation computers were
started to develop after 1991 AD. These
generation computers will combine
hardware and software to produce
Artificial Intelligence (AI) and will be
able to understand natural languages.
They will use Ultra Large Scale Integration (ULSI) and will have
super conductors using Gallium Arsenide (GA) or bio chips.
Intelligent knowledge based systems (IKBS) will be the main
feature of this generation computers. These computers will be
using optic fiber technology to handle Artificial Intelligence,
expert systems, Robotics, etc. Moreover, scientists are of opinion
that humans will turn into slaves of machine when this generation
computers start working completely.

Generations of computer 23

Features of the fifth generations computer

Bio chips and ULSI will be used as a memory component.
These computers will have the artificial intelligence.
These computers will be able to solve highly complex problems.
These computers will be able to understand natural languages.
Automatic programming, computational logic, pattern

recognition will be used.
These computers will use super conductor as a main storage unit.

Quick Learn!

¬¬ The fifth generation computer was developed after 1991.
¬¬ A British mathematician Alan Turing is one of the

founding fathers on theory and development of Artificial
Intelligence. 
¬¬ Intelligent knowledge based systems (IKBS) will be the
main feature of fifth generation computers.

Oral Evaluation

yy What is the memory device of fourth generation computer?
yy Tell the date from when the fourth generation computer

started to work?
yy Tell any three features of the fourth generation computer.
yy Tell any three features of the fifth generation computer.
yy What will the memory components of the fifth generation

computer be?
yy What is the full form of ULSI?



24 New Gateway to Computer Science 5

Let's Revise

áá The first generation computers were developed during
1946 to 1958 AD.

áá The benefit of vacuum tubes technology is that, it made
the onset of Electronic digital computer.

áá The first generation computers used vacuum tubes
(valves) as major electronic component.

áá The second generation computers were developed during
1959 to 1964 AD.

áá Transistors are smaller than electric tubes and have
higher operating speed.

áá The second generation computers used transistors as
major electronic component

áá The third generation computers were developed during
1965 to 1974 AD.

áá The third generation computer used Integrated Circuit
(IC) as its memory component.

áá The third generation computers were small in size, were
of low cost, had large memory and high processing speed.

áá The first microprocessor was developed by Intel
Corporation of the USA in 1971.

áá The present day computers that we see are the fourth
generation computers.

áá The fifth generation computer will combine hardware
and software to produce Artificial Intelligence (AI)

Generations of computer 25

Evaluation Time

1. Choose the best answer from the given alternatives.

a. Which was the memory component of the first generation
computer?

i. Vacuum tube ii. Integrated Circuit iii. RAM

b. W ho was the inventor of vacuum tube?

i. Lady Ada ii. Babbage iii. Lee De Forest

c. What was the memory component of the second
generation computer?

i. Transistors ii. Microprocessor iii. Mouse

d. Which generation computer use IC as its memory device?

i. Second ii. Third iii. Fourth

e. Which was the memory component of the fourth
generation computer?

i. Bio Chips ii. Microprocessor iii. Vacuum Tube

f. Which generation computer is on undergoing process of
development phase?

i. Second ii. Fifth iii. Fourth

g. Pentium IV is an example of :

i. Second generation

ii. Fourth generation

iii. Third generation

h. W ho was the inventor of IC?

i. Jack Kelby ii. Bin yon Hi iii. Babbage

26 New Gateway to Computer Science 5

i. Which generation computers were larger in size?

i. First ii. Second iii. Third

j. When was the first microprocessor developed by Intel
Corporation of the USA?

i. 1971 AD ii. 1971 BS iii. 2000 AD.

2. Write ‘True’ for correct and ‘False’ for the wrong
one.

a. Vacuum tube was developed by Lee De Forest.

b. The memory component of the second generation
computer was vacuum tube.

c. IC was the memory component of the third generation
computer.

d. Bio-Chips are the memory component for the fourth
generation computer.

e. Laptop computers are the example of the second
generation computers.

f. The fourth generation computers were started to use
form 1940 AD.

g. Transistors were the components of the second generation.

h. Apple/ Macintosh, DEC 10, Super brain and Cray X-MP
computers are the third generation computers.

i. IBM 1401 belongs to the second generation computer.

j. The first microprocessor was developed by Google
Corporation of USA in 1971.

Generations of computer 27

3. Fill in the blanks with suitable words.

a. The ………………….. generation computers were developed
during 1946 to1958 AD.

b. The first generation computers used ………………. as
major electronic component.

c. The ……………… generation computers were developed
during 1959 to 1964 AD.

d. …………….. are smaller than electric tubes and have
higher operating speed.

e. The …………………. generation computers were developed
during 1965 to 1974 AD.

f. The third generation computer used Integrated
……………………… as its memory component.

g. The first microprocessor was developed by Intel
Corporation of the USA in ……………AD.

h. The present day computers that we see are the
…………………. generation computers.

i. The ……………………………. generation computer will
combine hardware and software to produce Artificial
Intelligence (AI)

4. Complete the given table

Name of Memory Unit Duration Name of
generation computers
Transistors
First 1965-1974
Generation AD

28 New Gateway to Computer Science 5

IBM 3033,
Apple,
Pentium

Fifth
generation

4. Write down the full forms of the followings.

IC , LSI, VLSI, AI, IKBS, ULSI

5. Answer these questions.

a. What is the computer generation?

b. Name the various computer generations.

c. Write down the memory components of each generation
of computers.

d. Name any four computers used in the second generation.

e. Write any two features of each second and third
generation computer.

f. Write any three features of the fifth generation computer.

g. Name any four computers used in the fourth generation
computer.

Project Work

Prepare a summary chart to clarify the generation of
computer in the given format.

S.N. Generation Main Speed Language Devices
component used

1

2

3

4

5

Generations of computer 29

Unit 3 Types of
computer

Analog Computer Hybrid
Digital

Super Mainframe Mini Micro
computers Computers Computer Computer

Expected Competency
At the end of this unit, students will be able to,
¬¬ identify the types of computer.
¬¬ discuss the types of computer on the basis of work.
¬¬ discuss the types of computer on the basis of size.
¬¬ explain the features of different types of computer.

30 New Gateway to Computer Science 5

Introduction

Computers are classified in various ways. There are various types
of computer. People use different types of computer for different
purposes. Some people use computer for general purpose and
some use for special purpose. Special purpose computers are
applicable on particular application area and have limited area
for application like temperature recording, speed measurement,
telephone billing, etc. but general purpose computers are the
standard computers used for general application like word
processing, spread sheet, database application, internet access,
program development, etc.

Classification of computer

Computers can be classified in four different ways which are
listed below.

On the basis of work

On the basis of size

On the basis of brand

On the basis of model

In this unit, we are going to learn the types of computers on the
basis of work and size. There are three types of computers on the
basis of work and four types of computer on the basis of size.

On the basis of work

Analog Computer
Digital Computer
Hybrid Computer

On the basis of size � Mainframe computer
� Micro computer.
� Super computer
� Mini Computer

Types of computer 31

On the basis of work, we are using digital computer and on the
basis of size,we are using Microcomputer in our daily life.

On the basis of work

Analog Computer

An analog computer is a computer which
is used to process analog data. Analog
computer stores data in a continuous
form of physical quantities and performs
calculations with the help of measures.
It is especially used in scientific work,
medical and industrial field.

Features of analog computer

It is designed for specific task.
It has limited memory space.
The accuracy of this computer is poor.
It cannot do complex types of calculations.
It is operated by measuring physical quantities such as

voltage, temperature, pressure, speed, etc.

Digital Computer

The computer that works with
digital value 0 and 1 is called digital
computer. Where 0 is OFF and 1
is ON. Digital computer does not
measure the continuous data for
continuous output. Most of the
electronic systems are based on the

32 New Gateway to Computer Science 5

digital system. The entire PCs (Personal Computers) we are using
today on different fields are digital computers.
Features of digital computer

It works on discontinuous or discrete data.
It is applicable for general purpose.
It is based on the digits 0 and 1.
It is faster than analog computer.
It is highly accurate and reliable than analog computer.

Hybrid Computer

Hybrid computer has the
features of both analog and
digital computer. It works with
continuous and discrete value.
The qualities of analog and
digital computers are combined
on hybrid computer. These types
of computers are used on ICU
(Intensive Care Unit) of hospital,
Jet planes, etc.
Features of hybrid computer

It is expensive system
It is designed for special purpose so it is not so versatile.
It works on discrete and continuous value.
It has limited storage.
It is more complex than the other computer system.

Types of computer 33

Difference between digital and analog computer

Digital Computer Analog Computer

Itisageneralpurpose computer It is a special purpose computer

It has high accuracy It has low accuracy

It works with digits It works with physical values

It has a large storage capacity It has a very less storage capacity

It is expensive than analog It is cheaper than digital

computer computer

Quick Learn!

¬¬ There are four types of computers on the basis of work ,
size, brand and model

¬¬ On the basis of work, there are three computers analog,
digital and hybrid.

¬¬ Analog computers are designed for special task.

¬¬ The computer that works with digital value 0 and 1 is
called digital computer.

¬¬ Digital computer does not measure the continuous data
for continuous output.

¬¬ The qualities of analog and digital computers are combined
on hybrid computer.

34 New Gateway to Computer Science 5

Oral Evaluation

yy What are the types of computers on the basis of work?
yy What are the types of computers on the basis of size?
yy Tell any four features of analog computer.
yy Tell any two features of digital and hybrid computer.
yy Where are hybrid computers used?
yy Tell about digital computer.

On the basis of Size

Supercomputer

Supercomputer is the most powerful
and fastest computer among the
digital computers. This computer is a
special purpose computer which can
handle huge amount of calculations.
Supercomputer can solve very difficult
and complex problem within a Nano
seconds. Supercomputers are used to forecast the weather and
global climates.
Features of a super computer

It is one of the most expensive computers.
It is a special purpose computer.
It is used to forecast the weather and global climates
It can be used in automobile, aircraft, and space craft

designing.
It is used in military research and defence systems

Types of computer 35

Mainframe computer

It is a large and powerful computer. This
computer is developed to solve a large-
scale range of problems. It is primarily
used by large organizations. It is a general
purpose computer that is designed to
process large amount of data with very
high speed. More than 100 users can work
on this system.

Features of a mainframe computer

It is designed for large-scale data processing.
It is large in size than microcomputers.
It can support large number of terminals.
It is only suitable for large organizations.
It has a large memory and high processing speed.

Minicomputer

This computer is more powerful than
microcomputer but less powerful than
super and mainframe computers. It is
also multi-user computer and supports
more than dozens of people at a time. It
is more expensive than microcomputer.
It can accept all kinds of high level
languages to process the data.

Features of a minicomputer

It is more expensive than microcomputer.
It is used in small business organizations.

36 New Gateway to Computer Science 5

It can support more input and output unit than in
microcomputer.

It can support near about 50 other terminals.

Microcomputer

Microcomputers are the most
popular general purpose computers
which are mostly used on day to
day activities. Microcomputers are
popular as Home PC or Personal
Computer (PC) because these are
single user computers and mostly
used for personal use. These are popular among students,
professionals and home users due to small size, low price, and
low maintenance cost and easy in operation.
Features of a microcomputer

It is a general purpose computer.
It is mostly used for personal use.
It is cheaper and easy to carry.
It is easier to handle than other computers.
It is based on microprocessor.

Oral Evaluation

yy Tell about the supercomputer.
yy For what purpose are supercomputers used?
yy Tell about the microcomputers.
yy Tell any three features of the microcomputer.
yy Tell any three features of the minicomputer.

Types of computer 37

Some popular microcomputers

Laptop and Palmtop computers

Laptop and palmtop computers
are small sized digital handheld
computers. These are portable in size
than the desktop computers. These
computers consume less power
and have all the features of modern
personal computer. These computers
can also be operated by battery. They
have CD drive, floppy drive, modem
and other input/output sections.
The idea of laptop computer was
originated by Alan Kay but it was
developed in 1979 by William Moggridge. Palmtop computers are
helpful for remote area where there are no electricity facilities.
The higher authorities, social workers, researcher working in
remote areas get more benefits by palmtop or laptop computers.

Multimedia Computer

Multimedia computers

are the popular types of

microcomputers. Multimedia

is a combined form of two

or more Media like text,

graphics, sound, animation,

etc. Nowadays, the

38 New Gateway to Computer Science 5

multimedia PC is a choice of all. The multimedia computers are
optimized for high multimedia performance. They have high clock
speeds, primary and secondary memories to perform multimedia
operations. With the help of multimedia computers, we can work
with animation, games and other video editing tools.

Personal Digital Assistants (PDA)

These are small sized portable handheld
electronic device which have all the features
of personal computers. They have input,
processing, storage and output capability
like the other microcomputers. These can
be used as a diary, calendar, address book,
etc. We can transfer data from PDA to
personal computer and personal computer to PDA also.

Quick Learn!

¬¬ On the basis of size, there are four types of computers;
they are super, mini, micro and mainframe computers.

¬¬ A supercomputer is one of the most expensive computers
used for special purpose.

¬¬ Laptop, tablet, palmtop, multimedia, etc. are the examples
of microcomputer.

¬¬ A minicomputer also known as multi-user computer can
support more than dozens of people at a time.

¬¬ Laptop and palmtop computers are small sized digital
handheld computers.

Types of computer 39

Oral Evaluation

yy Name any three microcomputers.

yy Tell about laptop computer.

yy What is the full form of PDA?

yy Tell few lines about the multimedia computer.

yy Tell about multimedia.

Let's Revise

áá An analog computer is used to process analog data.
áá The analog computer stores data in a continuous form

of physical quantities and perform calculations with the
help of measures.
áá The computer that works with the digital value 0 and 1 is
called digital computer.
áá Hybrid computers have the features of both analog and
digital computer.
áá A hybrid computer works with continuous and discrete value.
áá Super computers are the most powerful and fastest
computers among all-digital computers.
áá Supercomputers are used to forecast the weather and
global climates.
áá Microcomputers are the most popular general purpose
computers which are mostly used on day to day activities.
áá Laptop and palmtop computers are small sized digital
handheld computers
áá Multimedia is a combined form of two or more media like
text, graphics, sound, animation, etc.

40 New Gateway to Computer Science 5

Evaluation Time

1. Choose the best answer from the given alternatives.
a. Which computer is used to process analog data?
i. Digital computer ii. Analog computer
iii. Hybrid computer
b. Which computer has the features of both analog and
digital computer?
i. Analog computer ii. Hybrid computer
iii. Digital computer
c. Which computer works on discontinuous or discrete
data?
i. Digital computer ii. Analog computer
iii. Hybrid computer
d. Which of the following computer is a special purpose
computer?
i. Analog computer ii. Digital computer
iii. Hybrid computer
e. Which computers are used to forecast the weather and
global climates.
i. Super computer ii. Micro computer
iii. Hybrid computer
f. Which of the following is a microcomputer?
i. Laptop computer ii. Analog computer
iii. Super computer

Types of computer 41

g. Which computer is popularly called as pc?

i. Super computer ii. Mainframe computer
iii. Micro computer
h. W hich of the following computer is based on
microprocessor?

i. Micro computer ii. Mini computer
iii. Super computer

2. Write True for correct and False for the wrong one.

a. There are two types of computers. They are general
purpose and special purpose computers.

b. Analog computers are used to process the analog data.
c. Analog computers are used for specific task.
d. Personal computers are analog computers.
e. A digital computer works based on 0 and 1.
f. Analog computers have the features of both digital and

hybrid computer.
g. Analog computers are cheaper than hybrid computers.
h. A supercomputer can solve very complex and difficult

problems within a millisecond.
i. A supercomputers are used to forecast weather and

global climates.
j. Mainframe computers cannot support large number of

terminals.
k. A minicomputer can accept all kinds of high level languages.
l. Microcomputers are easier to handle than other computers.
m. Laptop and palmtop computers are the examples of

supercomputer.

42 New Gateway to Computer Science 5

3. Fill in the blanks with suitable word.

a. An ………………….. computer is a computer which is used
to process analog data.

b. The computer that works with digital value 0 and 1 is
called ……………. computer.

c. Hybrid computers have the features of both ……………….
and digital computer.

d. ………………… computer works with continuous and
discrete value.

e. ……………….. are the most powerful and fastest computers
among the all-digital computers.

f. …………………….. can solve very difficult and complex
problem within a Nano second.

g. ……………….. are the most popular general purpose
computers which are mostly used on day to day activities.

h. ………….……. and ………………. computers are small sized
digital handheld computers

i. …………….. is a combined form of two or more media like
text, graphics, sound, animation, etc.

3. Answer the given questions.
a. What are special and general purpose computers?
b. Write down the name of computers on the basis of work
and size.
c. Define analog computer with its any two features.

Types of computer 43

d. What is a digital computer? Write any two features of
the digital computer.

e. What is hybrid computer? Write any two features of it.

f. Write any four differences between the digital and analog
computer.

g. Write any two features of the super and mainframe
computers.

h. Write any four types of microcomputers.

i. Write a few lines about the multimedia computer.

j. Write few lines about PDA.

4. Match the followings.

Super computer very easy to carry

Mini computer used to forecast the weather

Micro computer used in small business origination
Laptop computer used for large data processing
Mainframe computer general purpose computer

Project Work

Make a list of electronic devices that you use at your home.

44 New Gateway to Computer Science 5

Unit 4 Computer System

Printer Speakers Monitor

Webcam Computer Flash Drive
cases Keyboard and mouse
External
hard drives Router

Expected Competency

At the end of this unit, students will be able to,
¬¬ explain about computer system.
¬¬ tell about input, output and storage unit.

Computer System 45

Introduction

The combination of input unit, processing unit, output unit and
storage unit makes a complete computer system. The entire
input, process, output and storage unit must work together to be
a complete computer system. In the absence of any one unit, the
computer is incomplete. The combination of input unit, central
processing unit, output unit and secondary storage unit is called
computer system.

A computer system consists of two major elements: hardware and
software. The computer hardware is the collection of all the parts
that we can physically touch. The software is a set of instructions
for a computer to perform specific operations that we cannot
touch or feel. The hardware and software must work together to
perform the task given by the user.

Here, we are going to discuss the different units of computer
system.

Input devices

These devices are
used to give raw data
or instructions to the
computer system
for processing.
An input device
is a hardware or
peripheral device used to send data to a computer. An input device

46 New Gateway to Computer Science 5

allows the users to communicate and feed instructions and data
to computers for processing, display, storage and transmission.
Examples of input devices: Keyboard, Mouse, Scanner, Light
pen, Joystick, Touch pad, Touch screen, etc.

Central Processing Unit (CPU)

It is the brain or heart of the computer which does all the
processing activities in the computer system. The CPU consists
of three units.
Control Unit
Memory Unit
Arithmetic and logic unit (ALU)

Control Instruction
Unit Command

Command Primary
Memory

ALU Data
Result
CPU

Control unit

Control unit, is a typical component of the CPU that implements
the microprocessor instruction set. It extracts instructions from
the memory and decodes and executes them, and sends the

Computer System 47

necessary signals to the ALU to perform the operation needed.
The purpose of control unit is to run the whole computer which is
run by the instructions stored in RAM and ROM. So, the control
unit receives instructions which are stored in RAM and ROM and
controls operations of other connected units or devices through
those instructions.

The functions of control unit are listed below.

It control and co-ordinates the activities of other unit of the
computer system.

It fetches the instructions and data from memory unit and
executed the instructions one by one.

Memory Unit

The memory unit stores data to be processed, programs to be
executed and information to be output. Besides this, it stores
data and instructions for future use. Memory unit can store
instructions, data, and intermediate results. This unit supplies
information to other units of the computer when needed. It is
also known as internal storage unit or the main memory or the
primary storage or Random Access Memory (RAM). Primary
memory and secondary memory are the two types of memories
in the computer.

The functions of the memory unit are given below.

It stores all the data and the instructions required for
processing.

It stores intermediate results of processing.
It stores the final results of processing.

48 New Gateway to Computer Science 5