Let's Log In Computer Science Book 7 Revised (2078).indd

Approved by the Government of Nepal, Ministry of Education, Science and Technology,
Curriculum Development Centre, Sanothimi, Bhaktapur as an Additional Learning Material

vedanta

Computer Science

Book

7

Authors:

Sunil Kumar Gharti Sushil Upreti

vedanta

Vedanta Publication (P) Ltd.
jb] fGt klAns];g kf| = ln=

Vanasthali, Kathmandu, Nepal
+977-01-4982404, 01-4962082
[email protected]
www.vedantapublication.com.np

vedanta Book

Let's Log in 7

Computer Science

All rights reserved. No part of this publication may be reproduced, copied or
transmitted in any way, without the prior written permission of the publisher.

Authors: Sushil Upreti
Sunil Kumar Gharti

© Vedanta Publication (P.) Ltd.

Design: Manoz Manohar
First Edition: BS 2077 (2020 AD)
Second Edition: BS 2078 (2021 AD)

Printed in Nepal

Published by:

Vedanta Publication (P) Ltd.
jb] fGt klAns];g kf| = ln=

Vanasthali, Kathmandu, Nepal
+977-01-4982404, 01-4962082
[email protected]
www.vedantapublication.com.np

Preface

This is the age of information. Information Technology
has undoubtedly invaded all walks of life to such an extent
that computer and information literacy has become the
fundamental part of our daily activities. Computer Science
is now an essential addition to the school curriculum at all
levels.

Vedanta Let's Log in (A course in Computer Science)
is a series of ten books on Computer Science for basic
and secondary level students, designed for the need of
new generation to help acquire knowledge on the theory,
application and programming aspects of computing. This
series is based on the new syllabus of Computer Science,
designed and approved as per the curriculum prescribed
by Curriculum Development Center, Ministry of Education,
Government of Nepal.

The series covers the history of computer, its accessories,
applications and programming in LOGO and QBASIC in
a step-by-step and graded manner following logical and
scienti ic approach. Concept of graphic and web design is
also illustrated with many practical examples. This series not
only assists the students and the teachers in the class but also
incorporates latest information and developments in IT with
the present need of the students in Nepal. It also provides
other enthusiasts and learners with the skill and knowledge
to cope up with the growing demand of IT skills in market
and daily life.

We earnestly hope that the students would ind the journey
through this series an enjoyable experience and gain a sound
working knowledge on the basic aspects of computing and
information technology.

As far as possible, we have sincerely put in our efforts to
make the book error free. However, there is always scope
for improvement. Constructive criticism and feedback are
always welcome.

Authors

Table of Contents Page
No.
Lesson Topics
5
1 Computer Fundamental (History & Generation) 23
2 Types of Computer 32
3 Types of Software 40
4 Number System 47
5 Introduction to Operating System 61
6 Features of Word Processor 86
7 Features of Spreadsheet 108
8 Features of Presentation Software 124
9 ICT, Tools, and Cyber Ethics 130
10 Computer Virus and its Remedy 134
11 Introduction to Computer Network 146
12 Concept of Computer Graphics 162
13 Multimedia and its Uses 170
14 Concept of Program Designing Tools 181
15 Programming in QBASIC 193
195
Abbreviations
Model Questions (1-4)

Vedanta Let’s Log in Computer Science _ Book 7

Lesson Computer Fundamental

1 (History and Generation)

Introduction

At present, the world is rich in information. So, it has become a necessity
for everyone to know about computer. Computer is an electronic machine
capable of performing various tasks at a very high speed and with accuracy.
Computer processes the input data according to the given set of instructions
to give meaningful output.
Computer stores information and saves it for use in future. It is a
programmable machine designed to sequentially and automatically carry
out a sequence of arithmetic or logical operations.

Computers

History of Computer

The development of computer had started when people learned how to
count and calculate. Do you remember when we began learning? How do
we count? We used to count on our fingers. Early human also used stones,

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sticks, etc. to count. The history
of computer started with the first
concept of developing numbers and
counting. As the counting became
more complex and it could not be
done easily with the human fingers,
people started to develop various
types of counting devices. If we see
computer from the past to present,
we can see that they do not have
similar technology, shape, size, and Evolution of counting tools

functionality. So, the present computer that we use differs from the past
computer. A short description about the development process of computer is
described below:

Mechanical Devices

Abacus

Many centuries ago when humans started to
count the numbers, they thought of a device
which can trace numbers. Thus, Abacus came
into existence. It was the first counting device
which was developed in China more than 3000
years ago. The name Abacus was obtained from
Greek word Abax which means slab. This device
basically consists of a rectangular wooden frame
and beads. The frame is divided into two parts Abacus

and beam separates these parts. The upper part is called heaven and the
lower part is called earth.

The frame contains horizontal rods and the beads which have holes are
passed through the rods. Counting was done by moving the beads from one
end of the frame to the other.

Napier’s Bones

It is a device which contains a set of rods made of bones. It was developed
by John Napier in 1617, a Scottish Mathematician. Hence, the device was
named as Napier’s bones. The device was mainly developed for performing
multiplication and division. In 1614, he also introduced logarithms.

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John Napier Napier’s Bones

Slide Rule

Slide Rule was an analog device invented by William Oughtred in 1620.
The slide rule was used mainly for multiplication and division, and also
for "scientific" functions such as roots, logarithms, and trigonometry yet, it
was not usually used for addition or subtraction. The slide rule was based
on the work on logarithm. A simple slide rule consists of two movable
marked scales in which one scale slips upon the other.

William Oughtred Slide Rule

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Pascaline

Pascaline is a calculating machine developed by Blaise Pascal, a French
Mathematician in 1642. It was the first device with an ability to perform
additions and subtractions on whole numbers. The device is made up of
interlocked cog wheels which contain numbers 0 to 9 on its circumference.
When one wheel completes its rotation the other wheel moves by one
segment. Pascal patented this device in 1647 and produced it on mass scale
and earned a handful of money.

Blaise Pascal Pascline

Stepped Reckoner

Stepped Reckoner is a calculating machine designed in 1671 and built in
1673 by the German mathematician-philosopher, Gottfried Wilhelm Von
Leibniz. It expanded on the French mathematician-philosopher Blaise
Pascal's ideas and did multiplication by repeated addition and shifting. It was
the first calculator that could perform addition, subtraction, multiplication,
and division. Even square roots could be calculated by series of stepped
additions.

Gottfried Wilhelm Von Leibniz Stepped Reckoner

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Jacquard's Loom

Invented by Joseph Jacquard and first demonstrated in 1801, the Jacquard
Loom was an attachment for powered looms that uses a chain of punch
cards to instruct the loom on how to make intricate textiles. For example, a
loom could have hundreds of cards with holes in each of them that correspond
to hooks that can be raised or lowered to make textile brocade. This concept
of loom gave the idea of Binary Digits, 0 or 1 (Yes and No). This concept can
be considered as an important contribution to the evolution of the modern
computer. Below is an illustration of the Jacquard Loom attachment on top
of a textile loom.

Joseph Marie Jacquard Jacquard's Loom

Charles Babbage and his Engines

Charles Babbage was born on December 26, 1791 in London, England.
Charles Babbage, a professor of mathematics at the Cambridge University,
devised an automatic calculating machine called Differential Engine.
The first mechanical computer was called "Difference Engine". Difference
Engine was a machine that could solve polynomial equations without using
multiplication or division. He began developing the machine in 1822, and
worked on it for over ten years, but its construction was never completed.

Babbage’s next idea was the Analytical Engine. He invented and developed
his Analytical Engine in late 1833. This was the first general purpose fully
programmable mechanical machine. This device could perform complex
calculations and store the result. The analytical engine was based on the
principle of input, process, control, output, and storage . So, the modern

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computers are based on Babbage's idea and principle. Therefore,
Charles Babbage is also known as the father of modern computer
science.

Difference Engine Charles Babbage Analytical Engine

Lady Augusta Ada Lovelace

Lady Augusta Ada Lovelace suggested Charles
Babbage to use binary number system for
programs and data to be fed into the Analytical
Engine. It was the first programming concept.
So, she is regarded as the world's first computer
programmer. In 1979, the US Department of
Defense developed a programming language and
named 'ADA' to honor her.

Tabulating Machine

The Hollerith tabulating machine, also known Lady Augusta Ada Lovelace

as the tabulating machine, was an electrical
counting machine invented by Herman Hollerith. It was first described
in his doctoral thesis, which he presented at Columbia University in 1889.
The machine was proof of his concept that data could be encoded by holes
punched in a card and thereby counted and sorted electronically. The
machine was used to tabulate US census record in 1890 A.D. The tabulation
process was completed only in 3 years by the use of this machine which takes
approximately 10 years without the use of machine. Tabulating Machine
was the first of its kind to make practical use of the punched card in data
processing. It was successful: Hollerith went on to found the Tabulating
Machine Company, which later merged to become a company called

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International Business Machine (IBM), largest computer manufacturing
company.

Herman Hollerith Tabulating Machine

Electromechanical Computer

Mark I

Mark I was designed in 1937 by a Harvard graduate student, Howard H.
Aiken to solve advanced mathematical physics problems encountered in
his research. Aiken’s ambitious proposal envisioned the use of modified,
commercially-available technologies coordinated by a central control
system. The IBM Automatic Sequence Controlled Calculator (ASCC) IS
called Mark I. It was the first electromechanical computer. It was 51ft. long,
8ft. high, and 3ft. wide. It contained 1800 vacuum tubes.

Howard Aiken Harvard Mark-I

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Atanasoff-Berry Computer (ABC)

Atanasoff-Berry Computer, the ABC is considered the first electronic
digital computer. It was the first machine to use vacuum tubes.
Professor John Vincent Atanasoff and graduate student Clifford
Berry developed the ABC in 1937 and continued working on it until 1942
at the Iowa State College.

John Vincent Atanasoff Atanasoff Berry Computer Clifford Berry

Electronic Computers

Electronic Numerical Integrator and Calculator (ENIAC)

Electronic Numerical Integrator and Calculator, the ENIAC was the first
electronic computer used for general purposes, such as solving
numerical problems. It contained 18000 vacuum tubes as the main memory.
It could perform many complex arithmetic operations within a second.

John William Mauchly ENIAC John Presper Eckert

It was invented by J.Presper Eckert and John Mauchly at the University
of Pennsylvania to calculate artillery firing tables for the United States

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Army's Ballistic Research Laboratory. Its development began in 1943 and
was not completed until 1946. Although it was not completed until the end
of the World War II, the ENIAC was created to help with the war effort
against German forces.

Electronic Discrete Variable Automatic Computer (EDVAC)

John William Mauchly, John Presper Eckert developed EDVAC in
1952.

John Von Neumann EDVAC

A Hungarian mathematician, JohnVon Newman had already introduced
this concept in 1947 A.D. It contained a magnetic tape as the memory
device. It was based on binary number system. It is known as the first
stored program computer.

Electronic Delay Storage Automatic Computer (EDSAC)

Maurice Wilkes EDSAC

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EDSAC was the first operational stored program computer developed by
Professor Maurice Wilkes and his team. It was started in 1947 and executed
the first program in 1949 in Mathematical Laboratory at the University of
Cambridge. It contained 6000 vacuum tubes and it required 30 kilowatts of
electric power. This program used paper tape for in put and output results
were printed on a teletype page printer.

Universal Automatic Computer (UNIVAC-I)

Universal Automatic Computer,
the UNIVAC I, a trademark of the
Unisys corporation, was released in
1951 and 1952 by J. Presper Eckert
and John Mauchly. It was the first
electronic digital computer for
commercial users. It could handle
both numbers and alphabets. This
computer consisted of magnetic
tape for data input and output.
This computer was used for data
UNIVAC-I

processing until 1963. in America. It
contains thousands of vacuum tubes that utilizes punch cards and switches
for inputting data, and punch cards for outputting and storing data. The
UNIVAC later released the UNIVAC II, and III with various models.

All the above discussed conspicuous contributions were considerably
relevant in the development of computers in the modern world.

History of Computer in Nepal

There is not a long history of computers in Nepal. Nepal hired some types of
calculator and computers for its census
calculation. Following list shows its
history in Nepal.· In 2018 BS, an
electronic calculator called "Facit"
was used for census.· In 2028 BS,
census, IBM 1401, a second generation
mainframe computer, was used.·
In 2031 BS, a center for Electronic
Data Processing, later renamed to
National Computer Center (NCC),was

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established for national data processing and computer training. In 2038
BS, ICL 2950/10, a second generation mainframe computer, was used for
census. Today, probably each and every institution, business organization,
communication center, ticket counter etc. are using computers.
After 2039 B.S., microcomputers such as Sirus, Vector, IBM, Apple, etc.
were imported by private companies and individuals in Nepal. Today, there
are thousands of computer training institutes, computer sales, and repair
centers in Nepal. Different universities are operating IT colleges in Nepal.
Computer is included in the curriculum of school and colleges by CDC.

Generation of Computer

In computer terminology, generation refers to the development of the
technology. The generation term was used to distinguish between varying
hardware technologies. Nowadays, generation includes both hardware and
software, which together make up an entire computer system. Computer
generation is the classification of computers into different groups according
to their manufacturing date, other hardware, and software technology used
inside the computers. The five computer generations are:

Generation Time Main Component
First Generation 1940 to 1955 Vacuum Tube
Second Generation 1956 to 1964 Transistors
Third Generation 1965 to 1971 Integrated Circuits
Fourth Generation 1972 to 2010 Micro Processor
Fifth Generation 2010 to present Bio Chip

First Generation of Computers Vacuum tube

The period of first generation was from 1940-1955.
The computers of the first generation used vacuum
tubes as the basic components for memory and
circuitry for CPU (Central Processing Unit). These
tubes, like electric bulbs, produced a lot of heat and the
installations used to fuse frequently. Therefore, they
were very expensive and only large organizations were
able to afford them. Some computers of this generation
were ENIAC, EDVAC, UNIVAC, IBM-701, IBM-650,
etc.

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Second Generation of Computers

The period of the second generation
was from 1956-1964. In this generation,
transistors were used. They were
cheaper. They consumed less power. They
were more compact in size, more reliable,
and faster than the first generation
machines made of vacuum tubes. In
this generation, magnetic cores were
transistors

used as the primary memory, and
magnetic tape and magnetic disks as secondary storage devices.
In this generation, assembly language and high-level programming
languages like FORTRAN, and COBOL were used. Some computers of
this generation were IBM 1620, IBM 7070, CDC 1604, CDC 3600, UNIVAC
1108, RCA 501, etc.

Third Generation of Computers Integrated Circuit (IC)

The period of the third generation was from 1965-
1971. The computers of third generation used
Integrated Circuit (ICs) in place of transistors.
A single IC has many transistors, resistors, and
capacitors along with the associated circuitry.
Some computers of this generation were
IBM-360 series, Honeywell-6000 series, PDP
(Personal Data Processor), IBM-370/168, TDC-
316, etc.

Fourth Generation of Computers

The period of fourth generation was from
1972-2010. Computers of fourth generation
used Very Large Scale Integrated
(VLSI) circuits. This technology was first Very Large Scale Integrated

developed by American Intel Corporation. VLSI circuits on a single chip
made it possible to have microcomputers of the fourth generation. After
introduced of personal computers in 1981 by IBM, personal computers are
used in almost all the fields. Some computers of this generation were IBM
PCs, Apple/Macintosh PCs, SUPERBRAIN, DEC 10, STAR 1000, PDP 11,
Altair 8800, CRAY-1 (Super Computer), and CRAY-X-MP (Super Computer).

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Fifth Generation Computers

The period of the fifth generation is 2010 to
the present. In the fifth generation, VLSI
technology became ULSI (Ultra Large
Scale Integration) technology, resulting
in the production of microprocessor
chips having ten million electronic
components. This generation is based
on parallel processing hardware and AI
(Artificial Intelligence) software. AI is
an emerging branch in computer science,
which interprets the means and method
of making computers think like human Ultra Large Scale Integration

beings. Examples include Apple's Siri on the iPhone, and Microsoft's Cortana
on Windows 8 and Windows 10 computers. All the high-level languages like
C and C++, Java, and .Net are used in this generation.

AI includes Robotics, Neural Networks, Game Playing, Development of
expert systems to make decisions in real-life situations, natural language
understanding, etc.

Features of the Fifth Generation Computer

These computers are based on biochips.
They can think and decide themselves.
These computers are used in intelligent robots.
These computers have the ability to solve the problem themselves.
These computers can recognize voice, images, etc.
They have the ability to communicate by using natural languages.

1999 : The term Wi-Fi becomes part of the computing language and users
2003 : begin connecting to Internet without Wires.

The first 64-bit processor, AMD's Athlon 64, becomes available to
the consumer market.

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2005 : YouTube, a video sharing service, is founded. Google acquires
2006 : Android, a Linux-based mobile phone operating system.

2007 : Apple introduces the MacBook Pro, its first Intel-based, dual-core
2011 : mobile computer, as well as an Intel-based iMac. Nintendo's Wii
2015 : game console hits the market.

The iPhone brings many computer functions to the smartphone.

Google releases the Chromebook, a laptop that runs the Google
Chrome OS.

Apple releases the Apple Watch. Microsoft releases Windows 10.

POINTS TO REMEMBER

A computer is an electronic device that accepts the raw data, processes
raw data, and gives meaningful information.

Abacus was the first counting device developed in China more than 3000
years ago.

In 1617, Sir John Napier made a calculating device called Napier’s bones.
Slide Rule was an analog device invented by William Oughtred in 1620.
Pascaline, the first mechanical calculator, was invented by Blaise Pascal.
A German mathematician can philosopher, Gottfried Wilhem von Leibniz

improved the Pascaline by creating a machine that could also multiply.
Joseph Marie Jacquard invented an automatic weaving machine called

Jacquard Loom in 1801.
Charles Babbage invented the difference engine. He also invented the

first general-purpose computer called the analytical engine.
Charles Babbage is considered the father of modern digital computer.

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Lady Augusta Ada Lovelace suggested Charles Babbage to use binary
number system for programs and data to be fed into the Analytical
Engine.

Lady Augusta Ada is regarded as the world's first computer programmer.

The tabulating machine was an electrical counting machine invented by
Herman Hollerith.

Mark I was designed in 1937 by a Harvard graduate student, Howard H.
Aiken.

Atanasoff-Berry Computer, the ABC is considered the first electronic
digital computer and was the first machine to use vacuum tubes.

John von Neumann designed the Electronic Discrete Variable Automatic
Computer (EDVAC)

Electronic Numerical Integrator And Computer (ENIAC) was the first
general purpose electronic digital computer invented by John Mauchly
and J. Preseper Eckert.

Electronic Delay Storage Automatic Calculator, EDSAC is an early British
computer considered to be the first stored program electronic computer.

Universal Automatic Computer (UNIVAC) is the first commercial electronic
computer developed by J. Presper Eckert and John Mauchly.

In 2028 BS census, IBM 1401, a second generation mainframe computer,
was used in Nepal.

Computers are classified into different generation based on the
technology, their manufacturing date, hardware and software used.

Till date, there are five computer generations: first, second, third, fourth,
and fifth generation.

Machine language is known as the first generation of computer languages.
It is made up of only two numbers.

The first-generation computers used vacuum tubes: the second-
generation computers used transistors,the third-generation computer
used integrated circuits (ICs), the fourth-generation computer used Very
Large Scale Integrated (VLSI); and the fifth-generations computer used
ULSI (Ultra Large Scale Integration) technology.

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Computers with artificial intelligence are termed as the fifth generation
of computers.

AI is an emerging branch in computer science, which interprets the
means and method of making computers think like human beings.

Apple's Siri on the iPhone, and Microsoft's Cortana on Windows 8 and
Windows 10 computers are examples of AI.

Supercomputers have a very high storage capacity and high speed.

Exercise

1. Write very short answer to the following question.

a) Computer is electronic or electrical device?
b) What is abacus?
c) Who is called father of computer?
d) Who invented Pascaline?
e) Who is known as the first programmer?
f) What is Napier’s Bone?
g) Who was Lady Augusta Ada Lovelace?
h) Give any two examples of AI.
i) Write some features of the fifth generation computers.
j) Name the first computer brought to Nepal.
k) What is the major component of the second generation computer?
l) Write two examples of the fifth generation computer.

2. Write short answer to the following question.

a) Why is Charles Babbage known as the father of computer science?
b) Draw the figure of Abacus, showing its parts.
c) How are computer generations classified?
d) Define the term "artificial intelligence."

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3. Write long answer to the following question.

a) Describe the history of computer in Nepal in your own words.

b) What is computer generation? Discuss different generation of computer with
technologies used in each of them.

4. State whether the following statements are True or False:

a) Abacus was the first counting device.

b) Abacus is regarded as the first mechanical computing device.
c) Slide Rule was an analog device invented by Herman Hollerith

in 1620.

d) Joseph Marie Jacquard invented an automatic weaving machine.

e) Charles Babbage was the first computer programmer.

f) Pascline was developed by Blaise Pascal in 1642 A.D.

g) Herman Hollerith developed Mark-I for census.
h) Tabulating Machine was the first one to make practical use of the

punched card in data processing.
i) ENIAC was based on binary number system and it is known as the

first stored program computer.
j) The computers of first the generation used vacuum tubes as the

basic components.

k) ABC is considered the first electronic digital computer
l) IBM 1401 a third generation mainframe computer was used

in Nepal in 2028 Cencus.

m) The fifth generation computer will be based on artificial intelligence.

5. Match the following: Group 'B'

Group 'A'

i) Pascaline a) Howard H. Aiken

ii) Analytical Engine b) John Vincent Atanasoff and Cliff Berry

iii) Mark I c) Blaise Pascal

iv) ABC d) Charles Babbage

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6. Complete the following table of generations of computer.

Generation Main Component
First Generation
Second Generation
Third Generation
Fourth Generation
Fifth Generation

7. Write the full form of:

i) IBM ii) ASCC iii) ABC iv) ENIAC
viii) NCC
v) EDSAC vi) UNIVAC vii) AI xii) IC

ix) CDC x) HSEB xi) CPU

xiii) PDP xiv) VLSI xv) ULSI

8. Search three more words from the below puzzle word.

T RANS I S TORS
P S V B Y Y V K Y NM
X A UMD R B K Y Q X
R K S C VWD Z Q V T
D B N C A L RWP LW
MV V Z L B S Y YNX
NPDYJ I A I RTG
R L D G B Z NMB D B
D R Z P JMQ E D R L

1 First counting device
2 Developed by Blaise Pascal
3 Second generation computers used
4 Fourth generation computers used

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Lesson

2 Types of Computer

Introduction

There are different types of computer with different features. Computers
differ based on their ability of processing data. They are classified according
to purpose, data handling, and functionality. According to purpose,
computers are
a) Special Purpose Computers and
b) General Purpose Computers.

a) Special Purpose Computers

Special purpose computer is designed only to meet the requirements
of a particular task or application. The instructions needed to perform a
particular task are permanently stored into the internal memory so that it
can perform the given task on a single command.

On the basis of working principle

Analog Computer Digital Computer Hybrid Computer

On the basis of purpose On basis of size

Special Purpose General Purpose

Micro Mini Mainframe Super
computer computer Computer computer

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b) General Purpose Computers

General purpose computers are designed to meet the needs of many
different applications. In these computers, the instructions needed to
perform a particular task are wired permanently into the internal memory.
When one job is over, instructions for another job can be loaded into the
internal memory for processing. The general purpose machine can be used
to prepare pay-bills, manage inventories, print sales report, and so on.

On the basis of data types, they operate (Working Principle)

Based on the operating principles, computer can be classified into one of the
following types:

a. Analog Computer
b. Digital Computer
c. Hybrid Computer

a. Analog Computer Analog Computer

Analog computer is a special purpose
computer which can measure continuously
changing quantities, such as voltage,
pressure, temperature length height, etc.
It can perform a single task. For example,
automatic speedometer which display
speed of vehicles, voltmeter, analog watch,
seismograph, etc. are such computers.

b. Digital Computer Digital Computer

Digital computer is a general purpose
computer which solves problems which discrete
data. It works on digital values a binary digits:
0 and 1. It can perform many tasks according
to user requirements. IBM PC, Apple and
Macintosh computer are the example of digital
computer. On the basis of size and processing
speed, digital computers can be further
classified into four types: Microcomputer,
Minicomputer, Mainframe computer,
and Super computer.

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c. Hybrid Computer

Hybrid computer is a special purpose
computer that combines the best features
of both analog and digital computer. It
has significant capacity to work with
digital as well as analog signals. Such
computer is generally used for scientific
applications, airplanes, ships, hospitals,
and controlling the industrial processes.
Hybrid computer is used in hospital
to measure a patient’s vital signs like
temperature, heart rate, pulse, etc. It
converts into numbers and supplied to
the digital components that monitor the
patient’s vital signs. Electrocardiogram Hybrid Computer

(ECG) machine, Echocardiogram (ECHO) machine, ultrasound machine,
CT-Scan machine, Halter Monitoring machine are the examples of hybrid
computers.

Classification of Digital Computer

On the basis of size and processing speed, digital computers are classified
into four types. They are

i. Microcomputer,
ii. Minicomputer,
iii. Mainframe computer and
iv. Super computer

i. Micro Computer

Micro computer is also called PC (Personal Computer). Microprocessor
is used as its main processing unit (CPU). The first microcomputer was
IBM-PC which was designed by IBM (International Business Machine)
company. It is designed as single-user machine. Only one user can work
at a time with it. Micro computer are used at home, in school, in college, in
hospital, in offices, etc. Its examples include IBM PCs, Apple Mac., IBM
Compatible PCs (HP, Compaq, Dell, SONY, Toshiba), etc. Such computer
is further divided into the following categories:

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Desktop Computer
Laptop Computer
Handheld Computer

Desktop Computer Laptop Computer Handheld Computer

ii. Mini Computer Mini Computer

Minicomputer is more powerful and
expensive than micro computer. So, the
capabilities of a minicomputer is between micro
computer and mainframe computer. Such
computer is usually designed to serve multiple
users simultaneously (Parallel Processing). PDI-
1 was the first minicomputer designed by DEC
(Digital Equipment Crop) company in 1960. Its
examples include Digital Alpha, Sun Ultra, IBM
370, Honeywell 200, etc.

iii. Mainframe Computer

Mainframe computer is more powerful with large
storage and more expensive than minicomputer but less
powerful and costly than super computer. These computer
has multi-user and multi processor. It supports more than
100 of PC, such computer is used as serve on www (World
Wide Web) and also used in large organization, such as
bank, telecommunication, airlines, and universities for
large data processing. IBM is the major manufacturer
of mainframe computer. IBM 1401 mainframe computer Mainframe Computer
was brought for the first time to process census data in Nepal. IBM-2 series,
system 210 servers, CDC (Control Data Cyber) 6600, etc. are some popular
example of mainframe computer.

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iv. Super Computer

Super computer is the
most powerful and expensive
machine. It has the highest
processing speed than other
computers. It has parallel
processing for performing
any work. Such computers
are mainly used for weather
forecasting and global
climates, nuclear energy Super Computer

research, national security, biomedical research, aircraft design, robots
design, automobile design, military research, and other areas of science and
technology.

Sunway Taihulight is most powerful super computer from China. A
supercomputer is measured in terms of tens of millions Instructions per
second (mips). IBM Deep Blue, Titan, Seq voie, Cori, ETA-10, etc. are the
popular example of super computer.

POINTS TO REMEMBER

Computers are generally classified according to purpose, data handling,
and functionality.

Special purpose computer is designed only to meet the requirements of
a particular task or application.

General purpose computers are designed to meet the needs of many
different applications.

Based on the operating principles, computers can be classified into
Analog Computers, Digital Computers, and Hybrid Computers.

Analog computers can measure continuously changing quantities such
as voltage, pressure, temperature, length, height, etc.

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Digitalcomputerscanperformmanytasksaccordingtouserrequirements.

Hybrid computers are the special purpose computers that combine the
best features of both analog and digital computers.

On the basis of size, digital computers are classified into four types: Micro
computer, Minicomputer, Mainframe computer, and Super computer.

The first micro computer was IBM-PC which designed by IBM (International
Business Machine) company.

A micro computer is a small, single-user computer based on a
microprocessor.

Computer commonly used today are all digital computers.

The terms personal computer (PC) and microcomputer refer to any
computer meant for use by a single person.

Minicomputer is more powerful and expensive than micro computer.

Mainframe computers are multi-user and multi processor and support
more than 200 of PC.

Mainframes, minicomputers, and supercomputers are commonly used
by organizations and they support the computing needs of many users.

Supercomputer is an extremely fast computer that can perform hundreds
of millions of instructions per second. They have a large main memory.

Applications of supercomputers forecast weather and carry out other
scientific computing.

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xercise

1. Write very short answer to the following questions.

a. How is computer classified?
b. Write name of computer based on the working principles.
c. Which computer is used in hospital for Ultra Sound?
d. Which computer uses microprocessor?
e. Which type of computers comes in briefcase style?
f. Give one name of the most powerful super computer from China.

2. Write short answer to the following questions.

a. Differentiate between general purpose and special purpose computer with
suitable examples.

b. Define analog computer with examples.
c. What are digital computers? Where are they used?
d. List the type of digital computers.
e. Define minicomputer with examples.
f. Write the application of super computer.

3. State whether the following statements are True or False:

a) A special purpose computer can be used to prepare pay-bills.
b) Analog computer can measure continuously changing quantities.
c) Digital computer works on binary digits.
d) Microcomputer is the most powerful and fastest computer.
e) Minicomputers are designed to handle many users at a time.
f) Minicomputer is more powerful and expensive than microcomputer.
g) The computers we use at school are digital computers.
h) Laptop computers are heavy computers.
i) Hybrid computer combines the feature of microcomputer and

digital computer.

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4. Match the following Vedanta Let’s Log in Computer Science _ Book 7

Group 'A' Group 'B'
i) Micro computer a) Digital Alpha

ii) Minicomputer b) IBM Deep Blue

iii) Mainframe computer c) IBM-PC

iv) Super computer d) IBM1401

5. Select the best answer from the list of choices:

a. The computer which uses microprocessor is …………….

i) Micro computer ii) Super computer

iii) Mainframe computer iv) Mini computer

b. ECG (Electro Cardio Graph) is the example of …………… computer.

i) Analog ii) Micro

iii) Hybrid iv) None of above

c. ......................................... is mainframe computer.

i) IBM 1400 ii) IBM1401

iii) IBM1402 iv) IBM1403

d. The most powerful super computer is Sunway Taihulight from ……….

i) India ii) Germany

iii) China iv) America

e. Mainframe is more powerful and expensive than ……….. computer.

i) Micro ii) Super

iii) Mini iv) both i and ii.

6. Write the full form of: iv) DEC v) WWW vi) ECG

i) IBM ii) CPU iii) PC

7. Write short note of: b) Super computer
d) Hybrid computer
a) Analog computer
c) Micro computer

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8. Complete the crossword puzzle with the help of given clues.

1

3 2
4 5

ACROSS Personal computer
2 Can measure continuously changing quantities
3 Commonly used a computer today are
4 Extremely fast computer
5
Special purpose computers that combine the best features of both
DOWN computer
1

Activity

1. On a chart paper, show the classification of computer on the basis of
working principle.

2. Prepare a PowerPoint presentation on the following topics:
The world’s smallest computer.
Use and purpose of hybrid and supercomputer in different sectors.

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Lesson

3 Types of Software

Introduction

Software is the soul of computer. It is a collection of programs and
related data that provides the instructions to telling computer what to
do and how to do. Without it, the computer will never be useful. In other
word, software is an organized collection of programs, which is
responsible for controlling and managing the hardware components
of a computer system to perform specific tasks. Software is developed
to make the computer parts work together so that we can easily employ
computers to solve our problems and carry out day-to-day works.
Software is invisible and non-touchable part of computer system. It guides
and controls the hardware to carry out the instructions to perform the
different operations. Microsoft Word, Excel, Power Point, Adobe Page Maker,
Adobe Photoshop, QBasic, MS-Windows, Linux, Unix, etc. are examples of
computer software.

Different types of software

Generally computer software is classified into two major categories. They
are:

1. System Software
2. Application Software

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1. System Software

The system software is a collection of programs designed to manages,
operate, control, and extend the processing capabilities of the computer
itself. System software generates the user interface and allows the users
to interact with the hardware. System software is generally prepared by
the computer manufacturers. So, system software creates link between
user and computer. It is a platform for running application software. It can
be divided into operating system, utility software, device driver software,
language processor, etc.

a. Operating System Software Smart Phone

Operating system software is the system
software that manages and controls overall
operation of computer. It can co-coordinate,
control and manage computer hardware.
The popular operating system software's are
windows XP/ 7/ 8/ 10, Linux based fedora,
UNIX, MS-DOS, etc.

Android kitkat, Android Marshmallow, Android Oreo are the popular
operating system software of Android smart phone.

Operating system software functions between user and computer. Operating
system software are classified into two types as:

CUI (Character User Interface)

In this type of operating system software, user gives command or character
to perform the tasks. Keyboard is used to give command in this operating
system software.

GUI (Graphical User Interface)

In this type of operating system software, user gives command to perform the
tasks by clicking on icons, buttons, and menus using mouse. MS Windows
7/8/10, Linux, etc. are the example of GUI.

Operating system mainly performs the following tasks:

Memory management
Resource management

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Job scheduling
Input / Output handling
Process management
Interrupt handling
Security management

Operating System

b. Language Processor

System software converts high level language into machine level
language. It is called language processor. Three types of language processor
are:

i. Assembler

Assembler is a type of language processor which converts assembly
language into machine language. So, programmers develop easy writing
program by using assembly language. Mnemonic Code is used for writing
program in assembly language.

ii. Compiler

Compiler is a type of language which converts high level language into
machine level language whole at once. It displays all errors if them occur
in program. C, C#, C++, Visual Basic, FORTRAN, Java, etc. are compiler
based programming language.

iii. Interpreter

Interpreter is a type of language processor which converts the program
written in high level language into machine level language line by line.
QBASIC, BASICA, LISP, LOGO, etc. are interpreter based language.

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c. Utility Software

A set of programs that perform task related to the service of computer
software and hardware is called utility software. Utility software is also
called service program. The examples of utility software are: Antivirus
software, Backup Software, Archive, Data compression, WinZip, Register
Cleaner, Disk defragmenters, Disk partitions, etc.

Antivirus WinRar WinZip Disk Defragmenter Cleaner

2. Application Software

Application software is designed to fulfil the requirement of user. A
set of programs designed to do specific tasks is called application software.
Application software is further divided into two categories:

i. Package Software

The software developed for all general users to perform their generalized
tasks is called package software. Some of package softwares are MS Office
Package (MS-Word, MS-Excel, MS-PowerPoint), Adobe Photoshop, etc.

Microsoft office

Adobe Package Software 35

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ii. Customized/Tailored Software

The software which is designed to fulfil the specific requirement of an
individual or organization is called customized/tailored software. It can be
modified as per user's requirement. It can be used in school, college, hotel,
travel agency, airlines, hospital, and insurance.

POINTS TO REMEMBER

The combination of hardware and software to perform a task is called
computer system.

A program is a sequence of instructions written to solve a particular
problem.

The set of instruction or program to solve a problem is called computer
software.

The system software is a collection of programs designed to manages,
operate and control.

Operating system can co-coordinate, control and manage computer
hardware to computer system.

Keyboard is used to give command to CUI operating system software.

In GUI operating system software, user gives command to perform the
tasks by clicking on icons, buttons and menus using mouse.

System software that converts high level language into machine level
language is called language processor.

An assembler is a type of language processor which converts assembly
language into machine language.

Compiler is a type of language which converts high level language into
machine level language whole at once.

Interpreter is the type of language processor which converts the program
written in high level language into machine level language line by line.

A set of programs designed to do specific tasks is called application

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software.

The software developed for all general users to perform their generalized
tasks is called package software.

The software which is designed to fulfill the specific requirement of an
individual or organization is called customized/tailored software.

A set of programs that perform task related to the service of computer
software and hardware is called utility software.

Exercise

1. Write short answer to the following question.

a) Write the importance of software in computer.
b) What is software? Discuss types of software with example.
c) Define operating system software with examples.
d) List the types of system software.
e) What is utility software? Write name of utility software.
f) Define application software with its types.
g) Differentiate between system software and application software.
h) Write the special features of packaged software.
i) What is language processor? Write its types.

2. Fill in the blanks:

a) Software is a collection of ...........................
b) ........................... software takes care and maintains computer.
c) ........................... controls and manages all the internal operations of computer.
d) Computer system understands only ........................... language.

3. State whether the following statements are True or False:

a) Software is visible part of computer system.
b) Unix is the example of character user interface.
c) There are two types of application software.

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d) A set of softwares is called program.
e) System software provides easy interaction between user and

computer.

f) Every computer needs to have their own operating system.
g) Computer can only understand the program written in

assembly language.
h) Application software controls and manages overall internal

operation of computer system.

i) Android Kitkat is application software.

j) Backup software is an utility software.

k) Microsoft PowerPoint is an example of word processing software.

4. Match the following Group 'B'

Group 'A'

i) Utility software a) Marshmallow

ii) GUI b) Norton antivirus

iii) Android c) Windows 10

iv) Application software d) Ms Word

5. Select the best answer from the list of choices

a. Which is function of operating system?
i) Memory management
ii) Entertainment
iii) Word processing

b. Which is utility software?
i) Bank software
ii) Compiler
iii) Backup Software

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c. ............................... is not package software.

i) Ms office package

ii) Adobe Photoshop

iii) Windows8/10

d. Which software coordinates all the hardware and software?

i) Interpreter ii) windows 10 iii) antivirus

e. Which is application software?

i) DOS ii) Scan disk iii) MS Paint

g. Write the full form of

i) CUI ii) GUI iii) OS iv) MS DOS

6. Write short note of: b) Language processor
d) Operating system
a) Utility software
c) Tailored software

7. Write the single word for the following:

a) The collection of programs.
b) Software that manages all the internal operations of a computer.
c) Software converts program written other languages into machine language.
d) Software takes care and maintains a computer.

8. Complete the crossword puzzle with the help of given clues.

12
3

4 ACROSS
3 Language processor which
5
converts line by line into
DOWN machine level language
1 Character user interface 4 Language processor which
converts high level language
OS into machine level language
2 Utility software 5 Collection of programs

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Lesson

4 Number System

The concept of number system evolved when people used their fingers, sticks,
pebbles, and knots of rope to counting and do simple addition or subtraction.
In course of time, people used calculator and later computers for calculation.
The group of digits or symbols used to express quantities as the basis
for doing calculations is called number system.

Types of Number System

Today, different types of number system have developed and come in use.
Number system is differentiated by its base. The base is defined as the total
number of digits available in the number system. So, the number system is
divided into main four types on the basis of base as
1. Binary number system,
2. Octal number system
3. Decimal number system, and
4. Hexadecimal number system.

Number Systems

Decimal Binary Octal Hexadecimal

Digits: 0 to 9 Digits: 0, 1 Digits: 0 to 7 Digits: 0 to 9
Base 10 Base 2 Base 8 and A to F,
Base 16
40
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1. Decimal number system

The number system that we use in our life is the decimal number
system. Decimal number system has 10 digits from 0 to 9 with a base of
10. The successive positions to the left of the decimal point represent
units, tens, hundreds, thousands, and so on in decimal number system.

Each position represents a specific power of the base 10. For example, the
decimal number 765 consists of the digit 5 in the unit position, 6 in the tens
position and 7 in the hundreds position. Its value can be written as

(765) = (7×100)+(6×10)+(5×1)
10 = (7×102)+(6×101)+(5×10°)

= 700+60+5

=765

Binary number system

Computer is a machine which understands binary number. The number
system that used in computer system is the binary number system. Binary
number system has digits 0 and 1 and a base of 2. For example 1011 111
100 etc. 2, 2

, 2,

Octal number system

The number system that used in computer system to hold data on byte is
the octal number system. Octal number system has 8 digits from 0 to 7 and
a base of 8. For example 20 , 670 320 , etc.

8 8, 8

Hexadecimal number system

The number system that used in computer system to hold data is the
hexadecimal number system. Hexadecimal number system has 16 digits (10
digits and 6 letters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F) with a base of
16. Letters represent the numbers starting from 10 that is A = 10, B = 11, C
= 12, D = 13, E = 14 and F = 15. For example (7A1) , (5AC) , (BOD) , etc.
are some of the numbers in this system. 16 16 16,

Number System Conversion

People use commonly decimal number system. Computer use binary, octal,
and hexadecimal number system. We can't understand binary, octal, and

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hexadecimal number system. In this way, computer can not understand
decimal number system. So there are different methods to convert one
number system to another as:

Decimal to Binary Number System Conversion

To convert decimal number to binary number follows these steps:

Step 1 : Divide the given decimal number and write down the
remainder.
Step 2 : Divide quotient by 2 and again write down the remainder.
Step 3 : Repeat the process until quotient becomes zero.
Step 4 : Write the remainders bottom to top.

Examples:
i. (47) = (?)

10 2

2 47 Remainder

2 23 1

2 11 1

25 1

22 1

21 0

01

(46) = (101111)
10 2

ii. (24) = (?)
10 2

2 24 Remainder

2 12 0

26 0

23 0

21 1

20 1

(24) = (11000)
10 2

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Binary to Decimal Number System Conversion

To convert binary number to decimal number, follow these steps:

Step 1 : Multiply each binary digit with its place value
Step 2 : (Positive powers of two that is 20 ,21 , 22 ,23 , 24 ………)
Add all the products calculated in step 1 and total number is
decimal equivalent number.

Examples:

i. (11011) = (?)
2 10
(11011) = 1×24 + 1×23 +0×22+1×21 +1× 2°.
2
=1×16 + 1×8 +0×4 +1×2 +1× 1.
=16+8+0+2+1.
= (27)
10

ii. (10110) into Decimal
2
(10110) = 1×24 + 0×23 +1×22+1×21 +0× 2°.
2
= 1×24 + 0×23 + 1×22 + 1×21 + 0×2°

= 1×16+0×8+1×4+1×2+0×1

= 16 + 0 + 4 + 2 + 0

= 22

? (10110) = (22)
2 10

Decimal to Octal Number System Conversion

A positive decimal integer can be converted to octal through successive
division by 8 till the quotient becomes zero and sequential collection of
remainder at last comes first (i.e. bottom to top).

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Example:

i. (129) into Octal
10

Solution:

Remain
8 129

1
8 16 –

0 ?(129)10 = (201)
8
82 –

2
0

Octal to Decimal Number System Conversion

The procedure for conversion of octal numbers to their decimal equivalent
is similar to conversion of binary numbers to their decimal equivalents but
with the difference that the base used in this case is 8 instead of 2 used in
Binary.

Example:

(1026) into Decimal (weight)
8 1×83 + 0×82 + 2×81 + 6×8°

Solution:
Decimal Equivalent :

= 1×512+ 0×64 + 2×8 + 6×1

= 512 + 0 + 16 + 6

= 534

? (1026) = (534)
8 10

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POINTS TO REMEMBER

The group of digits or symbols used to express quantities as the basis for
doing calculations is called number system.

The base is defined as the total number of digits available in the number
system.

Decimal number system has a base of 10 as it uses 10 digits from 0 to 9.
Binary number system has a base of 2 as it uses 2 digits 0 and 1.
Octal number system has base 8 as it uses 8 digits from 0 to 7.
Hexadecimal number system has base 16 as it uses 16 digits (10 digits

and 6 letters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F).

Exercise

1. Answer the following questions:

a) What is number system?
b) Define base or radix of number system.
c) What is decimal number system?
d) What is binary number system? Why is it used in computer system?
e) What is octal number system?
f) What is hexadecimal number system? List its numbers and characters set.

2. State whether the following statements are True or False:

a) The base is defined as the total number of digits.
b) Decimal number system has a base of nine.
c) Octal number system has seven digits.
d) Binary number system uses 0 and 1.
e) Computer use binary, octal, and decimal number system.

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3. Match the following: Vedanta Let’s Log in Computer Science _ Book 7
Group 'B'
Group 'A'

i) Binary number system a) base 10

ii) Octal number system b) base 2

iii) Decimal number system c) base 16

iv) Hexadecimal number system d) base 8

e) base F

4. Convert the given numbers as indicated:

a. Decimal to Binary:

i. (44) ii. (98) iii. (178) iv.(227)
10 10 10 10

v. (675) vi. (875) vii. (1906)
10 10 10

b. Binary to Decimal:

i. (10110) ii. (101100) iii. (110011) iv. (10111)
2 2 22
vii) (11110111)
v. (1010101) vi. (111011) 2
2 2

c. Convert the following decimal numbers into octal numbers.

i. (422) ii. 252 iii. 115 iv. 119
10 vi. 861 vii. 528 viii. 699

v. 400

d. Convert the following octal numbers into decimal numbers.

i. (112) ii. 162 iii. 1437 iv. 151
8 vi. 361 vii. 154 viii. 1010

v. 940

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Lesson Introduction to

5 Operating System

What is an Operating System?

An operating system is the most important software that runs on computer.
It manages the computer's memory, processes, and all of its software and
hardware. Without an operating system, a computer is useless.

The Operating System's Job

Windows 10 Operating System

You've probably heard the phrase boot your computer, but do you know
what it means? Booting is the process that occurs when you press on the
power button to turn your computer on. During this process (which may
take a minute or two), the computer does several things:

It runs tests to make sure everything is working correctly.
It checks for new hardware.
It then starts up the operating system.
Once the operating system starts up, it manages all of the software
and hardware on the computer. Most of the time, there are many
different programs running at the same time, and they all need to access
your computer's Central Processing Unit (CPU), memory, and storage.

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The operating system coordinates all of this to make sure that each program
gets what it needs. Without the operating system, the software would not
even be able to talk to the hardware, and the computer would be useless.

Types of Operating Systems

Operating systems usually come preloaded on any computer that you buy.
Most people use the operating system that comes with their computer, but
it is possible to upgrade or even change operating systems.
Three most common operating systems for personal computers are Microsoft
Windows, Apple Mac OS X, and Linux.

Different Operating Systems

Modern operating systems use a Graphical User Interface, or GUI.
A GUI lets you use your mouse to click on icons, buttons and menus,
and everything is clearly displayed on the screen using a combination of
graphics and text.
Each operating system's GUI has a different look and feel. So, if you switch
to a different operating system, it may seem unfamiliar at first. However,
modern operating systems are designed to be easy to use, and most of the
basic principles are the same.

The Windows GUI The OS X GUI

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Before GUIs, computers had a command-line interface, which meant the
user had to type every single command to the computer, and the computer
would only display text.

CUI Screen

Operating Systems for Mobile Devices

The operating systems that we are talking
about were designed to run on desktop or
laptop computers. Mobile devices, such as
phones, tablet computers, and mp3 players
are very different from desktop and laptop
computers. So, they run operating systems
that are designed specifically for mobile
devices. Examples of mobile operating
systems include Apple iOS, Windows
Phone, and Google Android.

Microsoft Windows Operating System

Introduction

Microsoft Windows operating system is the Google Android
most popular operating system for personal
computers. It is a Graphical User Interface (GUI) based operating system.
GUI is a visual computer environment that uses graphics, icons, and pointers
to make computer more user friendly.

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GUI based operating system allows the user to interact with computer
through the graphical symbols or icons. In the GUI based operating system,
the user can supply the commands and instructions from the menu option
using pointing devices such as Mouse.

Microsoft Windows Operating system

The windows operating system allows user to open multiple programs at a
time in separate window. So, it is also called multi-tasking operating system.

Windows operating system is developed by Microsoft Corporation. A few of
the versions developed are Windows 95/98/NT/2000/XP/2003/Vista/7/8/10.
The latest one is Windows 10.

Some Features of Windows Operating System

It is easier for a new user to learn and use computer.
It is GUI based operating system where items are in graphical form.
It helps to run the multiple programs at a time on the same computer.
It supports a long filename.
It allows exchanging information between different applications.
It supports communication through Internet.
It helps to manage the files and folders very easily.

Windows Screen and its components

Desktop

Desktop is the initial screen. You see it after you start MS-Windows. It is
an on-screen work area that is displayed on the monitor when operating
system is loaded. You can use your desktop for almost any task, such as
opening programs, copying files, moving objects, stop tasks, and so on.
Desktop makes computer easier to handle in much the same way as you
were working on the physical desk. It consists of icons, shortcuts, taskbar,
and other shortcut tools.

50 Approved by Curriculum Development Centre, Sanothimi, Bhaktapur