New Gateway to Computer Science 7

Chapter ICT,Computer Ethics and
Cyber Crime
10

Learning Outcomes

At the end of this lesson, the students will be able to:
give the general concept of ICT and definition of ICT.
tell the uses of ICT.
write the means of communication.
discuss the computer crime and ethics.

Let's Update

. In 2003 AD, the first 64-bit processor, AMD's Athlon 64, became available
to the consumer market.

. In 2006 AD, Apple introduced the MacBook Pro, its first Intel-based, dual-
core mobile computer, as well as an Intel-based iMac.

. In 2009 AD, Microsoft launched Windows 7, which offered the ability to
pin applications to the taskbar and advanced in touch and handwriting
recognition, among other features.

Introduction

These days, computing tools are very important and powerful for us to
do our daily activities. Because of the computing tools there are lots of
challenges in this contemporary society. ICT (Information Communication
Technology) can be defined as the set of digital technological tools and
resources used to create, store, manage and communicate the information.

150 New Gateway to Computer Science Book- 7

These technologies includes telephones, mobiles, tablets, computers,
Internet, etc. Information & Communications Technology is a term that
covers all forms of computer and communications equipment and software
used to create, store, transmit, interpret, and manipulate information.

What is ICT?

ICT refers to technologies that provide us with access to information
through telecommunications. It is similar to Information Technology (IT),
but focuses primarily on communication technologies. This includes
the Internet, wireless networks, cell phones, and other communication
mediums. In the past few years, information and communication
technologies have provided society with a vast collection of new
communication capabilities. People can communicate in real-time with
others in different countries using technologies such as instant messaging,
voice over IP (VoIP), video-conferencing. Social networking websites
like Facebook, Twitter, Instagram, etc.
Modern information and communication technologies have created a
"global village," in which people can communicate with others across the
world.

ICT tools

Information Communication Technology tools are digital infrastructures
such as; computers, laptops, desktops, data projector, software programs,
cameras, printers, scanners and Interactive teaching items. ICT tools are
used in various fields like in education, communication, entertainment,
animation, business, sales and marketing, research, etc. The ICT tools are
becoming common these days for individuals as well as organizations.

Uses of ICT

Send and receive the information with the help of internet.
Distance learning and online education.

ICT,Computer Ethics and Cyber Crime 151

Online health service and medical advice.
Online business and shopping.
E-Commerce services.
E-Government services.
Outsourcing jobs.
Online communication like video
Product promotion/Digital Advertising

Means of communication

The following are the means of communications.

Computer System.
Radio, Television, Telephone, Mobile.
Email & Internet, Web sites, Social media.

Online news services and video conference.

Quick Learn!

¬¬ ICT (Information Communication Technology) can be defined as a
set of technological tools and resources used to communicate, create,
store, and manage information.

¬¬ An ICT technology includes telephones, mobiles, tablets,
computers, Internet, etc. which are mainly used for Information &
Communications.

¬¬ ICT refers to technologies that provide access to information
through telecommunications.

¬¬ Modern information and communication technologies have created a
"global village," in which people can communicate with others across
the world.

¬¬ Information Communication Technology tools are digital
infrastructures such as; computers, laptops, desktops, data projector,
software programs, printers, scanners and interactive teaching
items. 

¬¬ ICT tools are used in various fields like in education, communication,
entertainment, animation, business, sales and marketing, research
etc.

¬¬ The ICT tools are becoming common these days for individuals as
well as organizations.

152 New Gateway to Computer Science Book- 7

Cybercrime

Cybercrime is a criminal activity committed with the help of computer and
computing tools. Cyber terrorists use computer tools to steal the personal
information, spread viruses, hacking the web site and blogs to earn the
money. Computer crime is growing fast because of the rapid development
of technology. The growth of the technology is increasing in the volume of
cybercrime activities. These days people are also using social media like
facebook to commit criminal activities so that some countries are restricting
the use of social media. Cybercrime is committed by individuals or small
groups, as well as by criminal organizations that are often spread around
the world and committing crimes on an unprecedented scale.

Cyberlaw

Law is the principles and regulations established in a community by
authority and applicable to its people. Cyberlaw deals with the legal issues
of computer related crime like as online fraud, piracy, hacking, etc. Nepal
government also had issued cyberlaw in 2061 B.S. which is also known as
Electronic Transaction and Digital Act 2061 B.S. .

Computer Ethics

The history of computer ethics was started from 1950 AD. It is a branch
of applied science. Computer ethics deals with how the computer experts
should make decision regarding the social and professional behaviour
while working with the computer tools and technology. It also deals with
the procedures, values and practices that govern the process of consuming
computing technology and its related disciplines without damaging or
violating the moral values of any individual, organization or entity. Every
society has its rules about whether certain acts are ethical or not. These
rules have been established as a result of consensus in society and are often
written into laws.

ICT,Computer Ethics and Cyber Crime 153

Provisions of computer ethics 

1 Do not use a computer to harm other people.
2 Do not interfere with other people's computer work.
3 Do not snoop around in other people's files.
4 Do not use a computer to cheat others.
5 Do not use a computer to bear false witness.
6 Do not use or copy software for which you have not paid.
7 Do not use other people's computer resources without

authorization.
8 Do not appropriate other people's intellectual output.
9 Do think about the social consequences of the program you write.
10 Do use a computer in ways that show consideration and respect.

Quick Learn!

¬¬ Cybercrime is a criminal activity committed with the help of computer
and computing tools.

¬¬ The growth of the internet is increasing in the volume of cyber crime
activities.

¬¬ Cybercrime is committed by individuals or small groups, as well as
by criminal organizations.

¬¬ The history of computer ethics was started from 1950 AD.
¬¬ Computer ethics deals with how the computer experts should make

decision regarding the social and professional behaviour while
working with the computer tools and technology.
¬¬ Ethics also deals with the procedures, values and practices that
govern the process of consuming computing technology.

154 New Gateway to Computer Science Book- 7

1. Choose the best answer from the given alternatives.

a. ICT stands for:
i. Information Coming Technology
ii. Information Communication Technology
iii. Info communication Technology

b. Which of the following is related to communication technology?
i. Mobile Communication
ii. Television iii. Both

c. What is cybercrime?
i. Criminal Activities
ii. Intellectual Activities
ii. Internet and blogs

d. Which of the following is related to computer ethics?
i. Always creating problems
ii. Taking other’s resources

iii. Never use computer to bear false witness

2. State whether the given statements are true or false.

a. ICT (Information Communication Technology) can be defined as
a set of technological tools and resources used to communicate,
create, store, and manage information.

b. ICT refers to technologies that provide access to information
through telecommunications.

c. ICT tools are not used in various fields like in education,
communication, entertainment, animation, business, sales and
marketing, research, etc.

d. The ICT tools are becoming very unpopular these days for
individuals and organizations.

e. The growth of the internet is increasing in the volume of
cybercrime activities.

ICT,Computer Ethics and Cyber Crime 155

f. Cybercrime is committed by individuals or small groups, as well
as by criminal organizations.

3. Fill in the gaps with correct word(s).

a. An ICT technology includes telephones, mobiles, tablets,
computers, Internet, etc. which are mainly used for
………………………….

b. Modern information and communication technologies have
created a "……………….," in which people can communicate with
others across the world.

c. Information Communication Technology tools are ………………….
such as; computers, laptops, desktops, data projector, software
programs, printers, scanners and Interactive teaching items etc. 

d. ………………. is a criminal activity committed with the help of
computer and computing tools.

e. The history of computer ethics was started from ……………. AD.
f. ……………….. deals with how the computer experts should make

decision regard to the social and professional behaviour while
working with the computer tools and technology.
4. Answer the following questions.

a. What is Information Communication & Technology?
b. What are the uses of ICT?
c. Write any four means of communication .
d. What is cybercrime?
e. Define computer ethics? Also write the provisions of the computer

ethics.

Presentation Work

a. Conduct a speech competition on the topic “Role of Information
Communication and Technology”

156 New Gateway to Computer Science Book- 7

Chapter Computer Virus

11

Learning Outcomes

At the end of this lesson, the students will be able to:
define the computer virus.
explain the types of computer viruses.
write about the symptoms and protection from computer viruses.
identify antivirus programs.

Let's Update

. In 2011 AD, Google released the Chrome book, a laptop that run the Google
Chrome OS.

. In 2015 AD, Apple released the Apple Watch and Microsoft released
Windows 10 Operating system.

. In 2016 AD,  the first reprogrammable quantum computer was created.

Introduction

Computer virus is a destructive computer program that can destruct the
normal functioning of a computer copy itself and infect a computer system.
Computer viruses are small programs that are designed to replicate, attach
to other program, and damage and corrupt the computer programs. These
virus programs are placed into a commonly used program so that program
will run the attached virus program as it boots or open to execute. It is also
called a program or piece of code that is loaded onto your computer without
your knowledge and runs against the wishes of the user. When the virus
is executed, it spreads by copying itself into or over data files, programs,

Computer Virus 157

or boot sector of a computer's hard drive. Most of the computer viruses
will delete data, overwrite information, display messages, and add itself to
other files on the computer. Almost all computer viruses only damage the
data contained on the computer and do not physically harm the computer
or its hardware.

Types of viruses

Various types of computer viruses are explained below.

Macro Virus

A macro virus is a computer virus that spreads to other computers through
software programs that utilize macros. Microsoft word and excel are
two examples of applications that embedded in documents so they run
automatically when the documents are open.

Boot Sector virus

A boot sector virus infects the boot sector on hard disk, floppy disk and
also bootable media such as CD and DVD. The boot sector virus stays in
memory and infects storage media when they are written to by the infected
computer. When a computer starts up, it replaces the original boot record
programme. These are very difficult to remove. C-Brain, Stone, Disk killer,
Polyboot, etc. are the examples of boot sector virus.

File infector virus

It is a type of computer virus that inserts its malicious code into executable
files (EvE, .com, .BINek) on a system. When the infected file is opened or
used, the virus may overwrite the file and cause permanent damage to the
content of the overwritten file. Jerusalem, cascade, etc. are the examples of
file infector virus.

Script virus

A Script Virus is spread through webpages and has several properties such
as being easy to program, malicious, and highly transferable. These types of

158 New Gateway to Computer Science Book- 7

viruses are created with the help of scripting languages such as VB Script,
Java Script, etc. The script virus changes the scripting code in HTML
document of HTML. Redi of, I love you, Script viruses, etc uses email to
send themselves to others is also a form of worm.

Stealth virus

A stealth virus will hide itself in system memory every time a program
scanner is run. It employs various techniques to hide any changes so that
when the scanner looks for altered sections, the virus redirects it to any
area that contains the clean, uninfected data.  A more advanced anti-virus
program can detect a stealth virus.

Quick Learn!

¬¬ The computer virus is a destructive computer program that can
copy itself and infect a computer system.

¬¬ The computer viruses are small programs that are designed to
replicate, attach to other program, and damage and corrupt the
computer programs.

¬¬ Mostofthecomputerviruseswilldeletedata,overwriteinformation,
display messages, and add itself to other files on the computer.

¬¬ A macro is a series of commands that automatically triggers a
specific function within a software program. 

¬¬ The macro virus is initially embedded in one document or a few
documents, but it can spread to other documents within the same
computer.

¬¬ A boot sector virus infects the boot sector on hard disk, floppy disk
and also bootable media such as CD and DVD.

¬¬ C-Brain, Stone, Disk killer, Polyboot, etc. are the examples of boot
sector virus.

¬¬ File infector virus is a type of computer virus that inserts
its malicious code into executable files on a system.

¬¬ A stealth virus will hide itself in system memory in every time a
program scanner is run.

Computer Virus 159

Symptoms of virus infection

Computer will be slow down and do not response properly.
Computer will restart itself.
Unwanted error message appears on the display screen.
Programs and files may disappear from the computer system.
Disk and drive may not open properly.
Antivirus program may not work properly or may disappear from the

system.

Protection from computer viruses

Always use antivirus program on your computer system and update it
regularly.

Scan removable storage media with antivirus before using it.
Use firewall system.
Do not download unnecessary software and data from the internet.
Do not open unwanted and junk emails.
Give priority to use genuine software programs.

Antivirus software

Antivirus programs are utility tools used to detect and remove the virus
from the computer system. Most antivirus programs include both automatic
and manual scanning capabilities. The automatic scan checks the files that
are downloaded from the Internet, discs that are inserted into the computer,
and files that are created by software  installers. The automatic scan also
scans the entire hard drive on a regular basis. Some special functions of

160 New Gateway to Computer Science Book- 7

antivirus software are listed below.

It scans specific files or directories for any malware or known
malicious programs.

It allows us to schedule scans to automatically run.

It allows us to initiate a scan of a specific file, storage media or
computer at any time.

It removes malicious codes that are detected.

Some popular antivirus programs

Norton antivirus

Kaspersky antivirus

McAfee antivirus

NOD 32 antivirus

AVG antivirus

Panda antivirus

AVG antivirus

Quick Learn!

¬¬ If your computer is infected from the virus, your computer will be
slow down and do not response properly.

¬¬ If your computer is infected from the virus, antivirus program may
not work properly or may disappear from the system.

¬¬ To keep your computer safe from the virus attack, you always have
to use antivirus program on your computer system and update it
regularly.

¬¬ Never download unnecessary software and data from the internet
to keep is safe from the viruses.

¬¬ Antivirus programs are utility tools used to detect and remove the
virus from the computing devices.

¬¬ Most of the antivirus programs has the both automatic and manual
scanning capabilities.

Computer Virus 161

1. Choose the best answer from the given alternatives.

a. Which of the following is harmful for computer?

i. Anti virus ii. Virus iii. Freeware

b. The computer virus is simply a.................

i. disease ii. set of computer instructions or code

iii. type of bacteria

c. Which one is not a computer virus?

i. Trojan horse ii. logic bomb iii. McAfee

d. Special program which can detect and remove viruses from
computer is called

i. Virus ii. Anti virus iii. Groupware

e. Which of the following is antivirus program?

i. Norton ii. McAfee iii. Both i and ii.

f. Which of the following is a symptom of virus infection?

i. Computer will slower than normal time.
ii. Unwanted message appear on the screen
iii. Both i and ii.

2. State whether the given statements are true or false.

a. The computer antivirus is a destructive computer program that
can copy itself and infect a computer system.

b. Most of the computer viruses will delete data, overwrite
information, display messages, and add itself to other files on the
computer.

c. The stealth virus is initially embedded in one document or a few
documents, but it can spread to other documents within the same
computer.

d. A file infector virus infects the boot sector on hard disk, floppy
disk and also bootable media such as CD and DVD.

e. A stealth virus will hide itself in system memory in every time a
program scanner is run.

f. C-Brain, Stone, Disk killer, Polyboot, etc. are the examples of
script sector virus.

162 New Gateway to Computer Science Book- 7

g. If your computer is infected from the virus, antivirus program
may not work properly or may disappear from the system.

h. Never download unnecessary software and data from the internet
to keep it safe from the viruses.

3. Fill in the gaps with correct word(s).

a. ……………… are small programs that are designed to replicate,
attach to other program, and damage and corrupt the computer
programs.

b. A …………..is a series of commands that automatically triggers a
specific function within a software program. 

c. ……………… is a type of computer virus that inserts its malicious
code into executable files on a system.

d. If your computer is infected from the …………….., your computer
will be slow down and do not response properly.

e. To keep your computer safe from the virus attack you always have
to use …………… program on your computer system and …………..
it regularly.

f. …………………. programs are utility tools used to detect and remove
the virus from the computing devices.

4. Answer the given questions.

a. Define the computer virus. Write down a few examples of
computer virus.

b. What are the types of virus? Name them.
c. Write about macro virus, script virus and stealth virus.
d. What are the symptoms of virus infection?
e. What is the use of antivirus program? Write with examples.
f. Write down the functions of antivirus program?
g. Why is it essential to use antivirus software in our computing

devices?

Project work and Activity

a. Prepare a chart paper with the list of antivirus programs and paste it in
your classes.

b. Conduct a short presentation about “The role of antivirus program on the
computer system”.

Computer Virus 163

Chapter Introduction to Computer
Networking
12

Learning Outcomes

At the end of this lesson, the students will be able to:
explain the computer networking and its advantages and disadvantages.
tell the types of computer networking.
identify the network topology and its types.

Let's Update

. Facebook (A popular social networking) website was launched on February
4, 2004, by Mark Zuckerberg. He is also the founder of Facebook.

. YouTube was founded by Chad Hurley, Steve Chen, and Jawed Karim in
2005 AD.

Introduction

Networking is a collection of two or more
than two computers that are connected
together to share the data and resources.
A computer network is a set of connected
computers. Computers on a network are
called nodes. The connection between
computers can be done through cable or
wireless technology. Connected computers

164 New Gateway to Computer Science Book- 7

can share resources, like access to the Internet, printers, file servers, and
others. A network is a multipurpose connection, which allows a single
computer to do more task. We need sender, receiver, communication
channel, protocols and operating system to establish a computer networking.

Advantages

It is used for faster and cheaper communication services.

It is used to share the hardware and software resources like printer,
hard disk.

It has a flexible working condition.

It provides centralized administration and control.

It is easy to transfer files from one computer to another.

Disadvantages

The initial installation and administrative cost is high.

Difficult to control and maintain the privacy.

High chances of spreading the viruses.

Complicated to use and maintain in most cases.

Well trained technical support is required to handle it.

Types of computer networking

Computer networks can be categorized by their size as well as their purpose
of use. The size of a network can be expressed by the geographical area that
they occupy and the number of computers that are part of the network.
Networks can cover a single room to millions of devices spread across the
entire world. The types of network on the basis of the geographical locations
are explain below.

Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)

Introduction to Computer Networking 165

Local Area Network

A LAN is the connection of different
computers within a small area like
a room, building, School. LAN is
very useful for sharing resources,
such as software and hardware.
LANs can be built with relatively
inexpensive hardware, such as hubs,
network adapters and Ethernet cables. The smallest LAN may only use two
computers, while larger LANs can accommodate hundreds of computers. A
LAN typically relies mostly on wired connections for increased speed and
security, but the wireless connections can also be part of a LAN. High speed
and low cost are the defining characteristics of LANs.

Advantages of LAN

It is a reliable networking and suitable for very small area.

Adding and removing the computers is easy.

Data transfer rate is very high.

Easy to share software and hardware resources like printer, CD/DVD
etc.

It is easy to establish.

It is cheaper to establish.

Metropolitan Area Network

A metropolitan area network, or MAN, consists of a computer network
across an entire city or small region. A MAN is
larger than a LAN, which is typically limited to a
single building. Depending on the configuration,
this type of network can cover an area from several
miles. A MAN is often used to connect several
LANs together to form a bigger network.

Advantages of MAN
It is larger than LAN and smaller than WAN.

It is faster than WAN but slower than LAN.

Centralized administration is required to handle.

166 New Gateway to Computer Science Book- 7

Wide Area Network

WAN can contain multiple smaller networks,
such as LANs or MANs. The Internet is the
best example of a WAN. A wide area network,
or WAN, occupies a very large area, such as
an entire country or the entire world. The
Computers connected to a wide-area network
are often connected through public networks,
such as the telephone system. They can also
be connected through satellites. The largest
WAN in existence is the Internet.
Advantages of WAN
It is larger than LAN and WAN. It means it can cover large geographical

location.
Data and information can spread all over the world in a few minutes.
It is used to promote the business and services.

Quick Learn!

¬¬ A computer network is a set of connected computers. Computers on a
network are called nodes.

¬¬ A LAN is very useful for sharing resources, such as software and
hardware.

¬¬ The smallest LAN may use two computers only, while larger LANs
can accommodate hundreds of computers.

¬¬ A metropolitan area network, or MAN, consists of a computer
network across an entire city or small region.

¬¬ A MAN is larger than a LAN.
¬¬ WAN can contain multiple smaller networks, such as LANs or MANs.
¬¬ The Internet is the best example of a WAN.
¬¬ A wide area network, or WAN, occupies a very large area, such as an

entire country or the entire world.

Introduction to Computer Networking 167

Network Topology

A network topology is the physical layout or arrangement of the computers
in the networks. Network Topology refers to the layout of a network.
Topologies are either physical layout of devices on a network or the way
that the signals act on the network media.

Types of Topology

Bus topology

A bus topology is an arrangement in a local area network (LAN) in which
each node(workstation or other device) is connected to a main cable
or link. It uses the single main cable as a
backbone of network which has terminators
at the starting and ending points. All the
other nodes like workstations, peripherals,
etc. are connected to this main cable. This
type of topology is widely implemented in
LANs as it is easy and cheaper to install. It does not require much cabling
as in the other topologies like star and mesh. The main disadvantage of this
topology is that the entire network is dependent on the main cable. In case
some problem occurs in the main cable, the whole system gets affected.

Star topology

A star topology is a topology for a Local
Area Network (LAN) in which all nodes are
individually connected to a central connection
point, like a hub or a switch.  All nodes are
connected to each other only by the assistance
of this central hub. Installation and wiring is
easy in star topology. The functioning of the
star topology depends on the central hub. This
type of network is suitable for school, college,
hospitals, department store, small office, etc. The main drawback of the
topology is that, if the central connectivity device like hub or switch fails to
work, the entire networking system will fail to work.

168 New Gateway to Computer Science Book- 7

Ring topology
In Ring Topology, all the nodes are
connected to each-other in such a way that
they make a closed loop. Ring topology
is a kind of network topology in which
devices are connected in a ring and pass
information to or from each other. This
type of topology is highly efficient and
can handle heavier loads than bus topology. A ring topology also called
an active topology. All the devices are given the same importance in this
topology. It is in a shape of a ring, in which every node is connected to only
two neighbours. In case of any cable or device breaks away from the loop,
then it can be a serious problem for the entire network.

Quick Learn!

¬¬ A network topology is the arrangement of computers in the networks.
¬¬ Network Topology refers to the layout of a network.
¬¬ A bus topology uses the single main cable as a backbone of network

which has terminators at the starting and ending points.
¬¬ The main disadvantage of the bus topology is that the entire network

is dependent on the main cable.
¬¬ All nodes are connected to each other by the central hub in a star

topology.
¬¬ The process of installation and wiring is very easy in the star topology.
¬¬ In ring topology all the nodes are connected to each-other in such a

way that they make a closed loop.
¬¬ A ring topology also called an active topology.

Introduction to Computer Networking 169

1. Choose the best answer from the given alternatives.

a. Which of the following networking system is limited within a
room?

i. LAN ii. MAN iii. WAN

b. Which of the following networking system is larger than LAN?

i. MAN ii. WAN iii. Both

c. Which of the following is a networking topology?

i. Star ii. LAN iii. Network

d. Which computer network uses hub as a centre connectivity
device?

i. Ring ii. Bus iii. Star

e. In which network, if the hub or switch stops to work, then the
entire network stops to work?

i. Bus ii. Star iii. Ring

2. State whether the given statements are true or false.

a. A computer network is a set of connected computers. Computers
on a network are called nodes.

b. A LAN consists of a computer network across an entire city or
small region.

c. A MAN is smaller than a LAN.
d. The Internet is the best example of a LAN.
e. A network topology is the arrangement of computers in the

networks.
f. A network topology refers to the layout of a network.
g. All nodes are not connected to each other only by the assistance

of this central hub in a star topology.
h. In a bus topology, all the nodes are connected to each-other in

such a way so that they make a closed loop.
3. Fill in the gaps with correct word(s).

a. The smallest ……………….. may only use two computers, while
larger LANs can accommodate hundreds of computers.

b. …………….. can contain multiple smaller networks, such as LANs
or MANs.

c. A……………… occupies a very large area, such as an entire country
or the entire world.

170 New Gateway to Computer Science Book- 7

d. ………………… uses the single main cable as a backbone of network
which has terminators at the starting and ending points.

e. The main disadvantage of …………… topology is that the entire
network is dependent on the main cable.

f. A ring topology may also be called an ………………. topology
because messages are passed to each device in the ring.

4. Write down the single technical term for the followings.

a. Collection of two or more than two computers that are connected
together to share the data and resources.

b. A type of computer network that can contain multiple smaller
networks, such as LANs or MANs.

c. A topology that refers to the layout of a network.
d. This type of topology is widely implemented in LANs as it is easy

to install and does not cost much.
e. In this topology all the nodes are connected to each other only by

the assistance of the central hub.
f. A network topology in which devices are connected in a ring and

pass information to or from each other.
5. Answer the following questions.

a. What is computer network? Write it's any two advantages and
disadvantages.

b. What are the types of the computer network?
c. Define LAN with its advantages.
d. What is MAN? Write any four advantages.
e. Define WAN and write its advantages.
f. What is a network topology? Write down the types of network

topology.
g. Define bus, star and ring topology.

Presentation Work

a. Draw a figure of different network topologies in a chart paper and submit
them to your teacher.

b. Conduct a presentation about the LAN, MAN and WAN.

Introduction to Computer Networking 171

Chapter Introduction to Internet and

13 E-mail

Learning Outcomes

At the end of this lesson, the students will be able to:
write about the internet and its services.
tell about different internet terminologies such as www, web browser, web

server, web page, hyperlink, home page, etc.
define an e-mail, and tell its advantages.
create an e-mail account, check mails and compose mails.

Let's Update

. The domain name "YouTube.com" was activated on February 14, 2005
AD.

. The first YouTube video, titled “Me at the zoo”, was uploaded on April 23,
2005 AD.

Introduction

The internet has affected almost every
aspect of our lives amazingly within
a short period of time. We are able to
access new ideas, more information,
unlimited possibilities, and a whole new
world of communities due to it. It has
grown and evolved to influence how we
interact, how we conduct business, how we learn, and how we proceed our

172 New Gateway to Computer Science Book- 7

day to day activities. It has brought changes in our lives, in this process,
the Internet itself has changed too. In 1969, the ARPA (Advance Research
Project Agency) USA created a network which was called ARPANET. It
was a small size network in which only three university and government
agencies were connected.
The internet is also known as a network of networks. When two or more than
two computers are connected over the Internet, they can send and receive
all kinds of information such as text, graphics, voice, video, and computer
programs. Internet is a global network connecting mechanism where
millions of computers are connected together to share the information and
resources all over the world.

Internet services

An internet service allows us to access huge amount of information such as
text, graphics, sound, software, etc. There are various internet services that
offer exchange of information with individuals or groups. The followings
are the services of internet.
Electronic Mail : It is used to send and receive the mail all over the

world within a very short period of time.
Telnet: It is used to log on to a remote computer that is attached to the

internet.
Newsgroup: It offers a discussion forum for people to discuss on

various topics of their common interests.
Instant Messaging : It offers real time chat between individuals and

group of people like in facebook messenger, viber, etc.
World Wide Web (WWW) : WWW is also known as W3. It offers a

way to access documents spread over the several servers over the
internet. These documents may contain texts, graphics, audio, video,
hyperlinks.
Video Conferencing : Video conferencing or video teleconferencing is
a method of communicating by two-way video and audio transmission
with the help of telecommunication technologies.

Introduction to Internet and E-mail 173

Devices required for connecting the internet

A computer system.
Internet Service Provider (ISP) with user name and password.
Modem or Router.
Telephone system for ADSL technology.
Networking cables and Registered Jack.
Operating systems and software browsers.

Basic terminology on internet

WWW

The World Wide Web (WWW) refers to the collection of Web sites connected
to the Internet worldwide, together with the devices such as computers and
cell phones that access its content. It is based on these three technologies
they are Hyper Text Mark-up Language, Hyper Text Transfer Protocol and
web servers and browsers.

Web browser

A web browser is an application program used to access and view websites.
Microsoft Internet Explorer, Google Chrome, Mozilla Firefox, and Apple
Safari, etc. are the popular web browsers. The primary function of a web
browser is to view the web documents.

Web server

A Web server is a computer system that hosts websites. Most web servers
are connected to the internet through a high-speed connection or faster
data transmission rates. A fast internet connection allows web servers to
support multiple connections.

Web page

The web page documents are written in HTML (Hypertext Mark-up
Language) and are translated by web browsers. Web pages can either be
static or dynamic. Static pages show the same content each time they are
viewed. Dynamic pages have content that can change each time they are
accessed.

174 New Gateway to Computer Science Book- 7

Hyperlink

Hyperlink is an element in an electronic document that links to another
place in the same document or to an entirely different document. Typically,
you click on the hyperlink to follow the link. Hyperlinks are the most
essential element of all hypertext systems, including the World Wide Web.

Home page

A home page is the initial or starting page of a website or a browser. The
initial page of a website is sometimes called the main page as well as starting
page. We can use various links of home page to move on different page or
sections of website.

Quick Learn!

¬¬ The internet is also known as a network of networks.
¬¬ The internet is a global network connecting mechanism where millions

of computers are connected together to share the information and resources
all over the world.
¬¬ Electronic Mail is used to send and receive the mail all over the world with
a very short period of time.
¬¬ Telnet is used to log on to a remote computer that is attached to the internet.
¬¬ WWW offers a way to access documents spread over the several servers
over the internet.
¬¬ Video teleconferencing is a method of communicating by two-way video
and audio transmission with the help of telecommunication technologies.
¬¬ A web browser is an application program used to access and view websites.
¬¬ Microsoft Internet Explorer, Google Chrome, Mozilla Firefox, Apple Safari,
etc. are the popular web browsers.
¬¬ A Web server is a computer system that hosts websites.
¬¬ The web page documents are written in HTML (hypertext Mark-up
language) and are translated by Web browsers.
¬¬ Hyperlink is an element in an electronic document that links to another
place in the same document or to an entirely different document.
¬¬ A home page is the initial or starting page of a website or a browser.

Introduction to Internet and E-mail 175

Working with an Email

An electronic mail is the easiest way for exchanging the information with
one or more than one users. An email address is required to send and
receive email, and that address is unique to the user. Some people use
the internet-based applications and some of them use programs on their
computer to access and store emails. E-mail is a message that may contain
text, files, images, or other attachments sent through a network to a specified
individual or group of individuals. Some advantages of using email is listed
below.

It is available anytime and anywhere.
Delivery of message is very fast.
It has very limited cost.
It is very easy to use.
It can send and receive message instantly.
It is easy for record maintenance.
If the E-mail is not delivered, you will get the message failure

information.

Creating an Email

You can create your web-based free email account upon many sites. Some of
them are listed below. You can log on to any of these sites and then register
there as a new user.

http://www.gmail.com
http://www.outlook.com
http://www.yahoo.com

Creating Gmail Account

Get connected to the internet system.

176 New Gateway to Computer Science Book- 7

Now log on to the site http://www.gmail.com
To register for the very first time, click at create account.
Mtember registration form will appear as below.

Fill up the details and click on Next step.
A privacy and terms information box will appear.
Click on I agree.
Now Gmail will ask for the verification of the account as below.

Type your accurate phone number and click on continue to get the
verification code.

Enter the verification code that you have received on your mobile
number and click on continue.

Introduction to Internet and E-mail 177

Now, you will get a welcome screen as below.

Click on continue to Gmail button to create your final account.

Checking mails

Once you have created your email account, you can log on in it and view
your email.
Open any web browser.
Type the username and the password to log on in it and click on the

next button.

178 New Gateway to Computer Science Book- 7

Now, check your mails from inbox.

Sending Mails

We can use the following steps to send the mail.
Open the Gmail account at first.
In the top left, click on the Compose button.
In the "To" field, add recipients. If you want, you can also add recipients

in the "cc" and "bcc" fields.
Add a subject.
Write your message.
At the bottom of the page, click on the Send button.

Introduction to Internet and E-mail 179

1. State whether the given statements are true or false.

a. The internet is also known as a network of networks.
b. An electronic mail is used to send and receive the mail all over

the world within a very short period of time.
c. WWW offers a way to access documents spread over the several

servers over the internet.
d. A search engine is an application program used to access and

view websites.
e. An E-mail is a computer mailing system that hosts websites.
f. Hyperlink is an element in an electronic document that links to

another place in the same document or to an entirely different
document.

2. Fill in the gaps with correct word(s).

a. …………………. is a global network connecting mechanism where
millions of computers are connected together to share the
information and resources all over the world.

b. ……………….. is used to log on to a remote computer that is attached
to the internet.

180 New Gateway to Computer Science Book- 7

c. …………………… is a method of communicating by two-way video
and audio transmission with the help of telecommunication
technologies.

d. Microsoft Internet Explorer, Google Chrome, Mozilla Firefox,
and Apple Safari, etc. are the popular ………………….

e. The web page documents are written in HTML (hypertext Mark-
up language) and are translated by ……………..

f. A …………… page is the initial or starting page of a website or a
browser.

3. Answer the following questions.

a. What is the internet?
b. Write down the services of the internet.
c. What are the devices required for connecting the internet?
d. What is a web browser? Write with examples.
e. What is a web server?
f. Define web page and hyperlink.
g. What is a home page? What is the use of E-Mail?
h. Write down the process to check the Gmail account.
4. Lab Work

a. Visit a computer lab and search the information about the given
topic then paste it in MS-Word, Print it and submit to your
teacher.
»» Importance of Technology
»» History about the internet.
»» Computer virus

Presentation Work

a. Prepare a dialog between you and your friend describing about “The role
of the internet in teaching learning process”.

Introduction to Internet and E-mail 181

Unit 3

Computer Number
System

Decimal

Number Binary
System Octal

Hexadecimal

This unit cover the following chapter.
This unit covers the following chapters.
Chapter 14 Computer Number system

182 New Gateway to Computer Science Book- 7

Chapter

14 Computer Number System

Learning Outcomes

At the end of this lesson, the students will be able to:
tell about the computer number system.
explain the types of number system.
convert the various number systems.

Let's Update

. Twitter (A popular social networking web site) was founded on  March
21, 2006 AD by Jack Dorsey, Noah Glass, Biz Stone, and Evan Williams.

. Paul T. Buchheit is an American computer programmer and entrepreneur.
He was the creator and lead developer of Gmail.

Introduction

A set of values used to represent different quantities is known as Number
System.  The digital computer represents all kinds of data and information
in binary numbers. It includes audio, graphics, video, text and numbers.
The number of digits used in a number system is called its base or radix.
The base is written after the number as subscript such as (10101)2.

Computer Number System 183

Number Decimal Base 10 Number (0 – 9)
System Binary
Octal Base 2 Number (0 , 1)
Hexadecimal
Base 8 (0– 7)

Since data is stored in bytes
base 16 (0-9, A-F)

Types of number system

Binary Number system

A Binary number system has only two digits that are 0 and 1. It is also known

as base 2 number system. It is the mother language of the computer. Every

number (value) represents with 0 and 1 in this number system. The base of

binary number system is 2. Examples : (101010)2 , (1111000)2

Octal Number system

Octal number system has only eight digits from 0 to 7. Every number
(value) represents with 0,1,2,3,4,5,6 and 7 in this number system. The base
of octal number system is 8, because it has only 8 digits. Examples : (765)8

D, (e10c1i4m5)a8l Number system

Decimal number system has only ten digits from 0 to 9. Every number
(value) represents with 0,1,2,3,4,5,6, 7,8 and 9 in this number system.
The base of decimal number system is 10, because it has only 10 digits.

HExeaxmapdleesc:i(m97a8l)1N0 ,u(m01b45e9r)1s0 ystem

Hexadecimal number system has sixteen alphanumeric values from
0 to 9 and A to F. Every number (value) represents with 0,1,2,3,4,5,6,
7,8,9,A,B,C,D,E and F in this number system. The base of hexadecimal

184 New Gateway to Computer Science Book- 7

number system is 16, because it has 16 alphanumeric values. Here A is 10, B
is 11, C is 12, D is 13, E is 14 and F is 15. Examples : (DAD1)16 , (1DF4)16

Quick Learn!

Number system Base Used digits Example

Binary 2 0,1 (110011100)2
Octal
Decimal 8 0,1,2,3,4,5,6,7 (562)8
Hexadecimal
10 0,1,2,3,4,5,6,7,8,9 (9801)10

16 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F (ABC1)16

Conversion of number system

Conversion Table

Decimal Binary Octal Hexa-Decimal
0 0000 0 0
1 0001 1 1
2 0010 2 2
3 0011 3 3
4 0100 4 4
5 0101 5 5
6 0110 6 6
7 0111 7 7
8 1000 8 8
9 1001 9 9
10 1010 10 A
11 1011 11 B
12 1100 12 C
13 1101 13 D
14 1110 14 E
15 1111 15 F

Computer Number System 185

Conversion of binary numbers

Decimal to Binary

Divide the decimal value by 2 which is the base value of binary.
Write quotient under the number.
Write the remainder value in right side.
Continue the process till the quotient becomes 0.
Write the remainder from left to right in button to top sequence.

Example

Convert (55)10 into Binary 55
2 27 1
2

2 13 1

26 1

23 0

21 1

01

(55)10 = (110111)2
Binary to Decimal

Multiply the each digit with its base value and use addition (+) symbol
for each digit.

Keep the power starting from 0 in each base value from right most
digits.

Add all the products.

Example
Convert (0110111)2 into Decimal
= 0 × 26+ 1 × 25+ 1 × 24+ 0 × 23+ 1 × 22 + 1 × 21 + 1 × 20

= 0 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 1 × 2 + 1 × 1

= 0 + 32 + 16 × 0 + 4 + 2 + 1

= 55

(0110111)2 = (55)10

186 New Gateway to Computer Science Book- 7

Binary to Octal

Multiply each digit with its base value and use addition (+) symbol for each
digit. The next way to convert from binary to octal is to group binary digits
into sets of three, starting with the least significant (right most) digits.

Example

Convert (11100101)2 into Octal
Binary: 11100101 = 11 100 101 Making the grouping of three digits.

011 100 101 Place (0) in most significant digits if
necessary to complete a group of three
digits.

Then, look up each group in a table:

Binary: 000 001 010 011 100 101 110 111

Octal: 0 1 2 3 4 5 6 7

Binary = 011 100 101
Octal   = 3 4 5 = (345)8

Binary to Hexadecimal

To convert from binary to hexadecimal is to group binary digits into sets of
four, starting with the least significant (right most) digits.

Example

Convert (11100101)2 into Hexadecimal

Then, look up each group in a table:

Binary: 0000 0001 0010 0011 0100 0101 0110 0111
Hexadecimal: 0 1 2 3 4 5 6 7
Binary:
Hexadecimal: 1000 1001 1010 1011 1100 1101 1110 1111
8 9 A B C D E F

Binary Operation

We can convert the number system from one to another. Binary operation
means to perform the arithmetic operations like addition, subtraction,
multiplication and division using binary numbers. The addition and

Computer Number System 187

subtraction of the binary number systems are similar to that of the decimal
number system. The only difference is that the decimal number system
consists the digit from 0 to 9 and their base is 10, whereas the binary
number system consists only two digits that os 0 and 1.

Binary addition

It is the addition between or among the binary numbers 0 and 1. The rule
of binary addition is given below.

0+0=0

0+1=1

1+0=1

1 + 1 = 10

Let's consider the example.

ADD (11101)2 and (11011) Carry
1111
1 1 1 01

+1 1 01 1
1 1 1 000

The above sum is carried out by the following steps.

1 + 1 = 10 = 0 with a carry of 1.
1 + 0 + 1 = 10 = 0 with a carry of 1.
1 + 1 + 0 = 10 = 10 =0 with a carry of 1.
1 + 1 + 1 = 10 + 1 = 11 = 1 with a carry of 1.
so, the required result is 111000.

Binary Subtraction

It is the subtraction between the primary numbers 0 and 1. The rule of
binary subtraction is given below.

0–0=0

1–0=1

1–1=0

0 – 1 = 1 (with borrowing 1)

188 New Gateway to Computer Science Book- 7

For a binary number with two or more digits, the subtraction is carried out
column by column as in decimal subtraction. Also sometimes one has to
borrow from the next higher column.

Let's consider the example.

Subtract (1011)2 from (1100)2 Borrow
0 10 Minuend
Subtrahend
1 1 00 Difference
–1 0 1 1

00 01

The above Subtraction is carried through the following steps.

0 – 0 = 0
For 0 – 1 = 1, taking borrow 1 and then 10 – 1 = 1
For 1 – 0, since 1 has already been given, it becomes 0 – 0 = 0.
1 – 1 = 0
So, the result is 0001.

Binary Multiplication

It is the multiplication between or among the binary numbers 0 & 1. The
rules of binary multiplication is given below.

0×0=0

1×0=0

0× 1 = 1

1×1=1

Let's consider the given example.

Multiply (101)2 by (10)2 Multiplicand
101 Multiplier
×10
000 Product

+101
1010

So, the result is (1010)2.

Computer Number System 189

Binary Division

Binary division is a series of repeated subtraction using just as binary
multiplication. Binary division can be performed using the following tips.

Subtract the divisor from the dividend a number of times.
If subtraction is possible, put a 1 in the quotient and subtract the

divisor from the corresponding digits of the dividend.
If subtraction is not possible place 0 on the quotient.
Bring down the next digit from the dividend to add to the remaining

digits.

Let's consider the given example.

Divide (1110)2 by (10)2 Quotient
Dividend No remainder

Divisor 10 1 1 1 0 1 1 1
–10
11
–10
10
–10
××

So, the result is Q = 111 , Rem. = 0

Let's consider the given example

Divide (10110)2 by (110)2

Divisor 110 1 0 1 1 0 0 1 1 Quotient

000

1 01 1

–1 10

1010

–1 10

1 00 Remainder

So, the result is Q = 011 , Rem=100.

190 New Gateway to Computer Science Book- 7

1. State whether the given statements are true or false.

a. A set of values used to represent different quantities is known as
Number System. 

b. The digital computer represents all kinds of data and information
in decimal numbers.

c. The base of binary number is 8.
d. The base of decimal number is 10.
e. Computer processes data in binary form.
f. The binary and decimal use the same base value.
2. Fill in the gaps with correct word(s).

a. Decimal number has total …………….digits.
b. The base value of binary is ……………
c. (101010)2 is an example of ……….. number system.
d. (901)10is an example …………number system.
e. A binary number system has only ……..digits that are 0 and 1.
3. Answer the following questions.

a. What is a computer number system?
b. What are the types of number system?
c. What is the base value of binary and octal number?
d. What is the base value of octal and hexadecimal number system?
e. What is binary and decimal number system?
f. What is the difference between binary and decimal? Write with

examples.
4. Convert the following binary number into decimal number

system.

a. (101)2 b. (10101) 2 c. (11100) 2 d. (110011) 2
e. (110011) 2 f. (10011) 2 g. (1010101)2 h. (111110000) 2
5. Convert the following decimal number into binary number
system.

a. (122)10 b. (978)10 c. (512)10 d. (604)10
e. (111)10 f. (789)10 g. (1234)10 h. (500)10

Computer Number System 191

Unit 4
Computer Graphics and
Multimedia

This unit covers the following chapters.
Chapter 15 Computer Graphics
Chapter 16 Multimedia

192 New Gateway to Computer Science Book- 7

Chapter Computer Graphics

15

Learning Outcomes

At the end of this lesson, the students will be able to:
discuss about computer graphics and its application.
work with adobe Photoshop CC with the help of various tools.

Let's Update

. Viber Media was founded in  Tel Aviv,  Israel  in 2010 by  Talmon
Marcoand Igor Magazinnik.

. In 1975 AD, Bill Gates and Paul Allen launched Microsoft, which became
the world's largest PC software company.

Introduction

Computer graphic is the technology that deals with designs and pictures
on the computers. It is an art of drawing pictures, lines, charts, etc.
using computers with the help of some graphics software. Computer graphics
is made up of a number of pixels where pixel is the smallest element of
graphical picture. There are two types of computer graphics they are
Interactive Computer Graphics and Non Interactive Computer Graphics.
Interactive Computer Graphics involve two way communications between
the computer system and the user.  Non-interactive computer graphics is
the computer graphics in which a user does not have any kind of control
over the image. Computer graphics are any image media, usually movies
and pictures, which are created through the use of hardware and software.

Computer Graphics 193

Applications of Computer Graphics

In illustration and designing programs
Animation software
Desktop publishing
Web page designing
Drawing and painting programs

Understanding Abobe Photoshop

Photoshop is a graphic designing software developed by Adobe. With the
help of this software we can design, modify and edit the pictures. Photoshop
software provides many image editing features. It uses a layer-based editing
system that enables image creation and altering with multiple overlays
that support transparency. Shadows and other effects can be added to the
layers. Photoshop actions include automation features to reduce the need
for repetitive tasks. There are various versions with Photoshop such as
Photoshop 7, Adobe Photoshop CS, CC etc. We are going to discuss about
Photoshop CS here.

Starting Photoshop CC

In windows 7

Click on start button.
Choose all programs.
Select adobe folder and click on Adobe Photoshop CC.
Now, the Photoshop program will be loaded on your computer system.

In windows 8

Press the windows key and type Adobe Photoshop CC in search box
and press the enter key to open the Photoshop CC.

The Photoshop windows will display as below.

194 New Gateway to Computer Science Book- 7

Tools of Photoshop

Photoshop has various tools for the picture creating and editing. The tool is
always appearing at the left most side of the window. Let’s identify the tolls
of Photoshop.

1 Rectangular marquee tool: Make the image square or rectangular

2 Move tool: Move the picture or image.

3 Lasso tool: Free selection with the help of mouse. 1 2

4 Quick selection tool: Quick selection from the 3 4
brush tool. 6
5
8
5 Crop tool: Crop the image in required size. 7
10
6 Eye dropper tool: Select the colour from the 9 12
image. 14
11
16
7 Spot healing brush tool: Remove the spot 13 18
from the image. 20
15 21
23
8 Brush tool: Paint the image. 17

9 Clone stamp tool: Make clone and duplicate in 19
the selected area.
22

10 History brush tool: Apply synapse paint

11 Eraser tool: Remove any part of the image.

Computer Graphics 195

12 Gradient tool: Fill gradient from one colour to another colour.
13 Blur tool: Make image dim by deducting the pixel contrast.
14 Dodge tool: Bring lightness on the image.
15 Pen tool: Edit point location and draw any type of shape.
16 Type / Text tool: Type the text, symbols or characters.
17 Path selection tool: Select an export any part of image to other

application.
18 Rectangle tool: Draw a rectangle shape.
19 Hand tool: Move the image to the desire area.
20 Zoom tool: View the image in a larger or smaller size.
21 Toggle tool: Set the opposite colour.
22 Foreground colour tool: To apply the foreground colour.
23 Background colour tool: To apply the background colour.

Creating a new canvas/file

Click on the File menu.
Click on the New option. A new canvas window will appear as below.

Apply the required width, height, resolution and colour mode, etc. as
required.

Click on the Ok to apply it.
Now the new canvas will appear.

196 New Gateway to Computer Science Book- 7

Quick Learn!

¬¬ Computer graphic is the technology that deals with designs and
pictures on the computers.

¬¬ Computer graphics is made up of a number of pixels where pixel is
the smallest element of graphical picture.

¬¬ There are two types of computer graphics they are Interactive
Computer Graphics and Non Interactive Computer Graphics.

¬¬ Interactive Computer Graphics involve two way communications
between the computer system and the user.  

¬¬ Non-interactive computer graphics is the computer graphics in
which a user does not have any kind of control over the image.

¬¬ A photoshop software provides many image editing features which
uses a layer-based editing system that enables image creation and
altering with multiple overlays that support

Saving a graphics

We have to save the created new working
screen on Photoshop with the help of given
steps.
Click on the File menu.
Select the Save option.
A dialog box will appear as below.

Type the required file name on the file
name box and choose the picture format
from the format box.
Finally click on the Save button to apply.

Computer Graphics 197

Working with Photoshop Tools

Crop tool

It is a way of removing portions of a photo or
image to create focus or strengthen
the composition. We can use the Crop
tool to crop and straighten photos in Photoshop. 

Select the required part of the image.
Click on the crop tool from the tool box.
Click and drag on the required area of the image.
Double click the left mouse button or press the enter key to apply.

Lasso tool

This tool is used for free selection on the
image as you required.

Open the required image.
Click on the lasso tool from the tool

box.
Click on the picture and drag the mouse

to select the required area.

Eraser tool

Eraser tool is used to remove the certain area
or part of the image.

Open the required image.
Click on the eraser tool from the tool

box.
Click and drag the mouse to erase the

required portion of the image.

198 New Gateway to Computer Science Book- 7

Gradient tool

This tool is used to fill colours horizontally. We can use
this tool to create banners.
Open the required image.
Click on the gradient tool from the tool box.
Drag the mouse across the image.
Move towards left or right or as your desired

location to apply it.

Blur tool

You can also blur portions of your image to
emphasize and focus on a particular element.
It is used to reduce the extra pixel contrast and
make the image dim.
Open the required image.
Click on the blur tool from the tool box.
Choose the required brush from the

present picker.
Drag the mouse pointer over the part of the picture and release the

mouse.

Zoom tool

This tool is used to enlarge the size of the image. This tool is like a magnifying
glass.
Open the required

image.
Click on the zoom

tool from the tool
box.
Press CTRL + (+)
for zoom in [Larger
View] and CTRL + (-) for zoom out [smaller view] of the image.

Computer Graphics 199