Basic computer application in basic computer skills

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Basic Computer Skills
Chapter 1
Introduction to Computer

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Definition of Computer
• A computer:- is an electronic device, operating under the control of
instructions stored in its own memory that can accept data (input), process
the data according to specified rules, produce information (output), and
store the information for future use.
• The term ‘computer’ is derived from the word ‘compute’, which means to
calculate, or to count or to sum up.
• A computer can be defined as a machine (composed of electronic and
electric circuits), which can perform arithmetic operations and logical
decisions with defined pattern of instructions called software.

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Function of a computer
Any digital computer carries out five functions in gross terms:
Takes data as input.
 Stores the data/instructions in its memory and use them
when required.
 Processes the data and converts it into useful information.
Generates the output
 Controls all the above four steps

Functionalities of a computer(Contd.)
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Data Information
Processing

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Characteristics of Computer
1.Speed
2.Accuracy
3.Diligence
4.Storage Capability
5.Versatility

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Characteristics of Computer…
• Speed :The computer can process data very fast, at the rate
of millions of instructions per second.
• Accuracy: Computer provides a high degree of accuracy.
For example, the computer can accurately give the result of
division of any two numbers up to 10 decimal places.
• Diligence : When used for a longer period of time, the
computer does not get tired or fatigued. It can perform long
and complex calculations with the same speed and accuracy
from the start till the end.

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Characteristics of Computer…
• Storage Capability : Large volumes of data and information can
be stored in the computer and also retrieved whenever required.
A limited amount of data can be stored, temporarily, in the
primary memory. Secondary storage devices like floppy disk and
compact disk can store a large amount of data permanently.
• Versatility :Computer is versatile in nature. It can perform
different types of tasks with the same ease. At one moment you
can use the computer to prepare a letter document and in the
next moment you may play music or print a document.

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Computer Components
Hardware
Software
• Hardware
Computer hardware is the collection of physical elements
"Tangible objects” that constitutes a computer system.
The actual machinery, wires, transistors, and circuits … etc.

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Software
•is a computer programs, instructions anddata
which has been written to carry out a particular
task.

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Computer Units
1.Input Unit
2.Central processing Unit
3.Primary Memory Unit
4.Secondary storageUnit
5.Output Unit

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Input Devices
• Input device is any peripheral (piece of computer hardware
equipment to provide data and control signals to an information
processing system such as a computer or other information appliance.
• Input device Translate data from form that humans understand to
one that the computer can work with. Most common are keyboard
and mouse

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Example of Input Devices
Keyboard Mouse (pointing device) Microphone
Touch screen Scanner Webcam
Touchpads MIDI keyboard
Graphics Tablets Cameras Pen Input
Video Capture Hardware Microphone Trackballs
Barcode reader Digital camera Joystick
Gamepad Electronic Whiteboard
Note: The most common use keyboard is the QWERTY keyboard.
Generally standard Keyboard has 104 keys

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1) KEYBOARD
Definition:
―Keyboard is an input device that contains keys user press to
enter data or instructions in to the computer.
You enter most input data into the computer by using a keyboard.
This input method is similar to typing on a typewriter.

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KEYS OF KEYBOARD
Computer keyboards include keys that are designed to perform specific
tasks. These keys enable the user to perform complex tasks easily when using
the application. For example, many applications use a function key to access
online help for the user.
Keyboard keys consist of:
• Alphabetic keys • Numerical keys
• Symbols • Functional keys
• Extra keys

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 Alphabetic keys contain alphabets from A-Z & a-z
 Numerical keys contain numbers 0-9
 Symbols keys contain many symbols like !, @, #, $, % etc
 Functional keys contain f1-f12, design for special purpose will discuss latter.
 Extra keys contain Esc, Alt, Ctrl, Backspace, Enter etc

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2)MOUSE
Definition:
―Mouse is an input device that fits under palm of hand and Controls
movement of pointer.
The mouse is a palm-size device with a ball built into the bottom. The mouse
is usually connected to the computer by a cable (computer wires are
frequently called cables) and may have from one to four buttons (but usually
two).

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 Mouse come in many shapes and sizes. When you move the mouse over a
smooth surface, the ball rolls, and the pointer on the display screen moves in
the same direction.
 TYPES OF MOUSE
There are three types of mouse:
1.Mechanical mouse
2.Optical mouse
3.Wireless mouse

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A) MECHANICAL MOUSE:
The mouse that contains a metal or rubber ball on its underside.
When the ball is rolled in any direction, sensors inside the mouse detect this
motion and move the on-screen mouse pointer in the same direction.
B) OPTICAL MOUSE:
An optical mouse uses a light-emitting (laser) to detect movement relative to
the underlying surface.

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C) WIRELESS MOUSE:
Wireless mice usually work via radio frequencies commonly referred to as
RF. RF wireless mice require two components to work properly a radio
transmitter and a radio receiver.

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3) BIOMETRIC DEVICES
A "biometric device" is any device that measures a biological
function or trait.
It identifies persons seeking access to a computing system by
determining their physical characteristics through fingerprints,
voice recognition, retina patterns, pictures, weight, or other means.

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5)DIGITAL CAMERA
A digital camera can be used to take pictures. It can be hooked up to a
computer to transfer the pictures from the camera to the computer. It use
light sensitive processing chip to capture pictures or images.
We can save these images where ever we want can be a CD, Computer disk,
USB drive or can transfer from one computer to other computer or device.

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6) DIGITAL SCANNER
A scanner is used to copy pictures or other things and save them as
files on the computer. A scanner is similar to a photocopier, except
that instead of producing a paper copy of the document you place on
it, you get an electronic copy which appears on your computer
screen. This is very important input device use to convert a hardcopy
file (printed paper) to a softcopy (image or display file).

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Central Processing Unit
•CPU
•known as microprocessor or processor
•It is responsible for all functions and processes.

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CPU Components
• The CPU is comprised of three main parts:
1. ALU(Arithmetic Logic Unit)
2. Control Unit (CU)
3. Registers:Stores the data that is to be executed next.

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ALU
• Executes all arithmetic and logical operations.
• Arithmetic calculations like as addition, subtraction,
multiplication and division.
• Logical operation like compare numbers, letters, or special
characters

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Control Unit (CU)
Control Unit (CU): controls and co-ordinates computer
components.
• Read the code for the next instruction to be executed.
• Increment the program counter so it points to the next
instruction.
• Read whatever data the instruction requires from cells in memory.
• Provide the necessary data to an ALU or register.
• If the instruction requires an ALU or specialized hardware to
complete, instruct the hardware to perform the requested
operation.

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Registers
• Registers: Stores the data that is to be executed next, "very
fast storage area".

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Primary Memory
1. RAM.
2.ROM

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Primary Memory…
1. RAM: Random Access Memory: is a memory scheme within the
computer system responsible for storing data on a temporary basis,
so that it can be promptly accessed by the processor as and when
needed.
• It is volatile in nature, which means that data will be erased once
supply to the storage device is turned off.
• RAM stores data randomly and the processor accesses these data
randomly from the RAM storage.
• RAM is considered "random access" because you can access any
memory cell directly if you know the row and column that
intersect at that cell.

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Primary Memory…
2. ROM (Read Only Memory): ROM is a permanent form of
storage.
ROM stays active regardless of whether power supply to it is
turned on or off.
ROM devices do not allow data stored on them to be modified.

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Secondary Memory
•Stores data and programs permanently
•its retained after the power is turned off
•Main Examples
1. Hard Disk
2. Optical Disk
3. Flash memory

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Hard Disk
•Called Disk drive or HDD
•stores and provides relatively quick access to large
amounts of data.
•Stores data on an electromagnetically charged surface
or set of surfaces.

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Optical Disk & Flash
• anoptical disc drive(ODD) is adisk drivethat useslaserlight to
store data.
• There are three main types of optical media: CD, DVD, and Blu-
ray disc
CD “Compact Disk” can store up to 700MB
DVD “ Digital Video Disk “ can store up to 8.4 GB
Blu-ray disc. can store up to 50 GB

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3. Flash Disk
• A storage module made of flash memory chips.
A Flash disks have no mechanical platters or access arms, but the
term "disk" is used because the data are accessed as if they were on
a hard drive. The disk storage structure is emulated.
RAM V.s Hard Disk
• What are the differences between RAM as a main memory and
HDD as a Secondary Memory.

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Output Unit
• An output device is any piece of computer hardware equipment
used to communicate the results of data processing carried out
by an information processing system (such as a computer)
• converts the electronically generated information into human-
readable form.

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Output devices Examples
Monitor LCD Projection Panels
Printers (all types) Computer Output Microfilm (COM)
Plotters Speaker(s)
Projector

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1. Amonitor
CRT: Cathode Ray Tube
LCD: Liquid crystal display
most familiar these days

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MONITOR/DISPLAY DEVICES
Definition:
―Monitor or display devices are used to get output on screen. It is
like small television and available in different sizes and
specifications. The text which is displayed on screen is called
softcopy (as defined above).

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2. Printer:
•transfers data from a computer onto paper
Printer types:
1-Laser Printer.
2-Ink Jet Printer.
3-Dot Matrix Printer

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3) MULTIMEDIA/PROJECTORS
A Digital Projector/Multimedia is an elector-optical machine which converts
image data from a computer or video source to a bright image which is then
imaged on a distant wall or screen using a lens system. The cost of a device is
not only determined by its resolution, but also by its brightness.
The projector serves the following purposes:
• Visualization of data stored in a computer for presentations
• The projector replaces the white board as well as written documents.

Computer Classification
• Computers can be classified by size and power to:
1. Personal computer (PCs)
2. Workstation:
3. Minicomputer
4. Mainframe:
5. Super Computer
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• Personal computer (PCs): a small, single-user computer based on a
microprocessor.
In addition to the microprocessor, a personal computer has a keyboard for
entering data, a monitor for displaying information, and a storage device
for saving data.
• Workstation: a powerful, single-user computer. A workstation is like a
personal computer, but it has a more powerful microprocessor and a
higher-quality monitor.
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• Minicomputer: multi-user computer capable of supporting from 10 to
hundreds of users simultaneously.
• Mainframe: powerful multi-user computer capable of supporting many
hundreds or thousands of users simultaneously.
• Supercomputer: an extremely fast computer that can perform hundreds of
millions of instructions per second.
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• Compare between the previous type of computers based on
• Price
• Processing Speed
• Storage Capacity
• Powerful
• Single-user or Multi-user
• Computer Size
• Companies size
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Laptop computer
• is a portable computer.
• personal computer that can be easily carriedand used in a
variety of locations.
• run the samesoftwareand applications in PCs
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Netbook Computer
• Anetbookis a type of laptop that is designed to beeven more
portable.
• Cheaper and less powerful than laptops or desktops.
• They are generally less powerful than other types of computers,
but they provide enough power for email and internet access,
which is where the name "netbook" comes from.
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Mobile Devices
• A mobile device is basically anyhandheld computer.
• It is designed to be extremely portable.
• Some mobile devices are more powerful
• Types:
1.Tablet Computers
2.Smartphones
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Tablet Computers
• Designed to be portable.
• The most obvious difference is that tablet computers don't have
keyboards or touchpads.
• Best used for tasks likeweb browsing,watching videos,reading e-
books, andplaying games.
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Tablet Computers
• The most obvious difference is that tablet computers don't have
keyboards or touchpads. Instead, the entire screen is touch-sensitive,
allowing you to type on a virtual keyboard and use your finger as a mouse
pointer.
• Tablet computers are mostly designed for consuming media, and they are
optimized for tasks like web browsing, watching videos, reading e-
books, and playing games
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Smartphones
• a powerfulmobile phone
• designed to run a variety of applications in addition
to phone service.
• Compare it with the tablet?
• Internet accessis an important feature of
smartphones. (3G or 4G)(Wi-Fi Service)
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Data, Information and Knowledge
Data:
• Facts and figures which relay something specific ,but which
are not organized in any way and which provide no further
information regarding patterns
•unstructured facts and figures
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Information:
• For data to become information, it must be
contextualized, categorized, calculated and condensed.
(Processing)
• it is data with relevance and purpose.
Knowledge:
• Knowledge is closely linked to doing and implies know-
how and understanding.
• Processing Information
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• Data: symbols
• Information: data that are processed to be useful; provides answers
to "who", "what", "where", and "when" questions
• Knowledge: application of data and information; answers "how"
questions
Processing data produces information, and processing information
produces knowledge.
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CHAPTER TWO
SOFTWARE AND PROGRAMING LANGUAGES
Software
• Software is a generic term for organized collections of computer
data and instructions, often broken into two major categories:
1. system software
2. application software

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System software
Known as Operating System
is responsible for controlling, integrating, and managing
the individual hardware components of a computer system
Windows is an example of OS.
example of System Software:
1) Microsoft Windows 2) Linux
3) Unix 4) Mac OSX
5) DOS

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Application software
•is used to accomplish specific tasks other than just
running the computer system.
•It may consist of:
• a single program, such as an image viewer;
• a small collection of programs (often called a software
package) that work closely together to accomplish a task,
such as a spreadsheet or text processing system;
• a larger collection (often called a software suite) of related but
independent programs and packages that have a common user
interface or shared data format, such as Microsoft Office,

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PROGRAMING LANGUAGES
A language in simple word is a way of communication for any
person to other person in order to understand his talk.
Definition:
A language used to write instructions for the computer. That is the
way of representation any program in to that form which is
understandable by CPU.
Reminder: program is written instruction for computer.

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TYPES OF PROGRAMMING LANGUAGES
According to structure, interface and procedure computer
languages can be divided in to two major types.
1. Low Level Language
2. High Level Language
1)LOW LEVEL LANGUAGE
Low level language is also called machine language. That types of
languages are close to machine and easily understand by machine
as, it is majorly in binary form (0 & 1).
Low level language types are: -
-->Machine language
-->Assembly language

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 MACHINE LANGUAGE
This program written is this type of language sometimes referred to as
machine code or object code, machine language is a collection of binary
digits or bits that the computer reads and interprets. Machine language is
the only language a computer is capable of understanding. Machine code is
consisting of 0 & 1, which mean off and on bit.
Program written in machine language is very fast but machine dependent. It
is also referred as First Generation Language.
―

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 ASSAMBLY LANGUAGE
Assemble language is also low level language close to machine language. It is
also referred as assembly or ASL, assembly language and Second Generation
―
Language.
Assembly language used to interface with computer hardware. Assembly
language uses structured commands as substitutions for numbers allowing
humans to read the code more easily than looking at binary.
Although easier to read than binary, assembly language is still a complex
language.

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2. HIGH LEVEL LANGUAGE
High level programming languages is languages program than use languages
or syntax which closes to human languages so; it is easy to understanding the
languages. This type of language is machine-independent, and uses similar
language as English, which is easily understandable by human.
This type of language’s processing is slow as compared to low level
languages. As, it need any translator between interface on computer and
human. So, that both can understand their languages.

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CHAPTER THREE
COMPUTER NETWORK AND INTERNET
COMPUTER NETWORK
DEFINATION:
―A computer network is a group of computers which are connected
together to allow communication between them.
TYPES OF NETWORK
There are two main types of network:
• LAN
• WAN

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LOCAL AREA NETWORK (LAN)
Definition: “A network which is located entirely on one site such as
an office, school or within a group of buildings that are in close
proximity that are connected together.
WIDE AREA NETWORK (WAN)
“A network which connects together computers on a number of sites
in different areas.
A WAN or Wide Area Network is a group of
Widely dispersed computers that are connected together. These
could be across the same town, or across a country or even across the
world.

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ADVANTAGES OF NETWORK
SPEED
Networks provide a very rapid method for sharing and transferring
files. Without a network, files are shared by copying them to
memory cards or discs, then carrying or sending the discs from one
computer to another. This method of transferring files can be very
time-consuming.
COST
Networkable versions of many popular software programs are
available at considerable savings when compared to buying
individually licensed copies.

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SECURITY.
Files and programs on a network can be designated as "copy
inhibit," so that you do not have to worry about illegal copying of
programs. Also, passwords can be established for specific
directories to restrict access to authorized users.
RESOURCE SHARING.
Sharing resources is another advantage of school networks. Most
organizations cannot afford enough laser printers, fax machines,
modems, scanners, and CD players for each computer. However, if
these or similar peripherals are added to a network, they can be
shared by many users.

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ELECTRONIC MAIL.
The presence of a network provides the hardware necessary to
install an e-mail system.
E-mail aids in personal and professional communication for all
personnel, and it facilitates the dissemination of general information
to the entire staff.
Electronic mail on a LAN can enable students to communicate with
teachers and peers at their own institute.
If the LAN is connected to the Internet, we can communicate with
others throughout the world.

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FLEXIBLE ACCESS.
Networks allow users to access their files from computers
throughout the institute.
Like Students can begin an assignment in their classroom, save
part of it on a public access area of the network, then go to the
media center after school to finish their work.
Students can also work cooperatively through the network.

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NETWORK TOPOLOGY
Network topology refers to the layout used to wire the computers together.
TYPES OF TOPOLOGY
There are four main topologies that are used.
1. 1.BUS
2. 2.STAR
3. RING
4. MESH
1. BUS TOPOLOGY
Each computer is connected to a single cable which
connects all of the computers. All nodes (file server,
workstations, and peripherals) are connected to the linear cable.

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Advantages of Bus Topology
• Easy to connect a computer or peripheral to a linear bus.
• Requires less cable length than a star topology.
Disadvantages of a Bus Topology
• Entire network shuts down if there is a break in the main cable.
• Terminators are required at both ends of the backbone cable.
• Difficult to identify the problem if the entire network shuts
down.
• Not meant to be used as a stand-alone solution in a large
building.

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2. STAR TOPOLOGY
―All communication takes place via a central computer or HUB device.‖
A star topology is designed with each node connected directly to a central
network hub, switch, or concentrator.
Data on a star network passes through the hub, switch before continuing to
its destination. The hub, switch, or concentrator manages and controls all
functions of the network. It also acts as a repeater for the data flow.

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Advantages of a Star Topology
Easy to install and wire.
No disruptions to the network then connecting or removing
devices.
Easy to detect faults and to remove parts.
Disadvantages of a Star Topology
Requires more cable length than a linear topology.
If the hub or concentrator fails, nodes attached are disabled.
More expensive than bus topologies because of the cost of the HUB
device.

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3. RING TOPOLOGY
Each computer is connected to the two computers on either side of it. The
last computer is linked to the first to form a ring.
Advantages of a Ring Topology
• Easy to install and wire.
• Equal Access to devices no one computer will use all the bandwidth
• Easy to detect faults and to remove parts.

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Disadvantages of a Ring Topology
 Slow since signals goes in sequential order
 If the concentrator fails, nodes attached are disabled.
 Single break in cable can disrupt the flow of network.

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Mesh Topology
In the mesh topology, every node has a dedicated point-to-point link to
every other node. Messages sent on a mesh network can take any of several
possible paths from source to destination.
A mesh topology provides redundant communication paths between some
or all devices (partial or full mesh).

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Advantages of Mesh Topology
• The use of large number of links eliminates network congestion.
• If one link becomes unusable, it does not disable the entire
system.
Disadvantages of Mesh Topology
• The amount of required cabling is very large.
• As every node is connected to the other, installation and
reconfiguration is very difficult.
• The amount of hardware required in this type of topology can
make it expensive to implement.

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INTERNET
Definition:
Internet is global Network of Networks. The internet is a
―
worldwide public network of computers on which people can
join and use multiple services such as sharing of information.
By internet users at any one computer can get information
from any other computer.

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CHAPTER-FOUR
MALICIOUS SOFTWARE
Computer Viruses
Trojan horses
Worms

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Viruses
• A computer virus is an application program designed and
written to destroy other programs.
•A virus is a small piece of software that piggyback on real
programs.
•virus might attach itself to a program such as a spreadsheet
program and it has the chance to reproduce (by attaching to
other programs)

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Trojan horses
Simply a computer program.
The program claims to do one thing (it may claim to be a
game) but instead does damage when you run it.
Unlike a computer virus or a worm – the trojan horse is a
non-replicating program that appears legitimate.
After gaining the trust, it secretly performs malicious and
illicit activities when executed.

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Worms
A worm is a small piece of software that uses computer
networks and security holes to replicate itself.
A worm is a malicious software which similar to that of a
computer virus is a self-replicating program, however, in the
case of worms, it automatically executes itself.
Worms spread over a network and are capable of launching a
cumbersome and destructive attack within a short period.

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How do you know if you have a virus?
• Lack of storage capability
• Decrease in the speed of executing programs
• Unexpected error messages
• Halting the system

Tips to avoid viruses and lessen their impact?
1. Delete e-mails from unknown or suspicious, untrustworthy
(unreliable) sources, especially those with files attached to an e-
mail.
2. Never open a file attached to an e-mail unless you know what it
is, even if it appears to come from a friend.
3. Download files from the Internet only from legitimate and
reputable sources.
4. Update your antivirus software at least every two weeks as over
200 viruses are discovered each month.
5. Backup your files periodically
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