Summary Notes
TERM TWO
BASIC SEVEN
7
ACADEMIC YEAR 2013/2014
Prepared by Sir Lexis Oppong
INFORMATION PROCESSING
DATA: - Data is a collection of raw
unorganized facts such as numbers, text,
audio(sound), video and images. Raw data may
not be meaningful and useful to the user.
Therefore we need to manipulate, arrange and
organize these raw data into a form that is
meaningful and useful to the user. This
meaningful and useful form of a processed data
is referred to as INFORMATION.
Therefore we define information as processed
data.
INFORMATION. – Information is defined as
processed data that is meaningful and useful
to the user. Examples of information include
newsletters, reports, movies, invoices,
calendars, etc. When data is processed the
result is information.
What is Information Processing?
Information processing is the process of
manipulating, arranging and organizing
data into information.
Prepared by Sir Lexis Oppong
STAGES OF INFORMATION PROCESSING
CYCLE
Information processing cycle of a computer
is a set of steps the computer follows to
receive data, processes the data according to
instructions from a program, displays the
resulting information to the user, and stores
the results.
The information processing cycle has
various stages, each stage involves one or
more specific components of a computer.
Prepared by Sir Lexis Oppong
CPU
INPUT
MOUSE
PROCESSING
STORAGE
RAM
OUTPUT
MONITOR
INPUT STAGE (Data Stage)
Computer Input Stage is when a computer
accepts whatever that is entered or fed into
its system. Input can be supplied by a
person(such as by using a keyboard) or by
another computer or device( such as
diskettes, flash drives, memory cards, CDROM, etc.). Devices that help input data and
commands are called INPUT DEVICES.
Examples of input devices and the data they
input to the computer are shown in the table
below.
INPUT DEVICE
NAME
DATA
MOUSE
COMMANDS
KEYBOARD
TEXT
MICROPHONE
SOUND
THE PROCESSING STAGE
This is the stage where the data that is inputted in
the computer is organized, manipulated and
structured to form information. This stage is
where the real processing of data into
information occurs and is therefore considered as
the most important stage.
On a computer the device that performs this
processing is called the Central Processing
Unit(CPU).
The CPU is the brain and the heart of the
computer.
A computer process is a systematic series of
actions a computer uses to manipulate data.
It does all the calculations and manipulations of
the computer. The CPU is found inside the system
unit. Examples of processors are the Pentium,
Centrino and Core Duo.
Prepared by Sir Lexis Oppong
THE STORAGE STAGE
A computer must store data so that it is available
for processing. This storage location can be (the
hard disk drive or C:\, and the floppy drive or
A:\). The storage of data in the computer is called
online storage while the storage of data on
computer tapes, diskettes, flash drives, CD-ROMs
is called offline storage.
STORAGE STAGE is when information is stored for
future use. Devices for storing information are
called Storage Devices.
Prepared by Sir Lexis Oppong
The primary storage device of the computer is
called a Hard Disk Drive. Other storage devices
are the CD&DVD-ROM, flash drives, external
hard drives, etc.
THE OUTPUT STAGE
Computer output stage is when the computer produces
processed data or information. OUTPUT can be in
different formats, such as paper, diskette, or disc or on
screen.
After the computer has finished processing the
data into information, it needs to show or give the
information to the user. Devices used to output
information are called output devices. Some
examples of output devices are shown in the table
below.
OUTPUT DEVICE
NAME
MONITOR
LOUDSPEAKERS
PRINTER
USE
Displaying
text, pictures,
etc.
Outputting
sound
Printing text
and pictures
onto a paper
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PARTS OF A PERSONAL COMPUTER
THE COMPUTER
A computer is a general purpose machine that
helps us to process information. There are several
different categories of computers such as
• Minicomputers
• Mainframe computers
• Supercomputers
• Network computers
• Personal computers (Microcomputers)
SUPERCOMPUTERS
MAINFRAME COMPUTERS
MINICOMPUTERS
THE PERSONAL COMPUTER
A Personal computer is a system of many
components. These come together to make the
personal function effectively and efficiently. It is
also known as a microcomputer or simply a PC
meaning personal computer. It is called personal
computer(PC) because it has been purposely
designed to be used by one person at a time.
USES
Personal Computers can be used for many
different things such as typing documents, playing
music and even factory automation.
GROUP OF PERSONAL COMPUTERS
Personal Computers are grouped into three. These
are
• Personal Digital Assistants(PDAs)
• Laptop Computers
• Desktop Computers
A. PERSONAL DIGITAL ASSISTANT
Personal Digital Assistants are hand-held
computers that are used to perform simple tasks.
They are small in nature and are used to take
notes, serve as a reminder, and sometimes even
used to browse the net. These days most PDAs also
serve as mobile phones.
B. LAPTOP COMPUTERS
Laptop computers perform all the functions that a
regular computer does. Laptop computers are
popular because they are portable and be carried
everywhere. They also operate on batteries and
used (for a specified period) even when there is no
electrical power.
C. DESKTOP COMPUTERS
By far the most popular type of personal
computers is desktop computers. They are used in
schools, homes, banks, hospital and other social
gatherings.
The personal computer can be grouped under two
main components. These are hardware and
software.
THE PERSONAL COMPUTER HARDWARE
Hardware refers to the physical components
required for creating, using, manipulating and
storing electronic data. Examples system unit,
monitor, printer, mouse, keyboard, etc. Because
personal computer hardware is used to facilitate
information processing, they can be grouped into
four
INPUT DEVICES
SYSTEM UNIT
For inputting data
Contains parts for processing data
STORAGE DEVICES
OUTPUT DEVICES
For storing data
For displaying results
INPUT DEVICES
Input devices are parts of the computer system that
are used to feed data into the computer. These
parts serve as the link by which the human user
can issue instructions or feed the computer with
data. Input devices translate data from a human
form into a computer form. The most common
input devices are the keyboard and the mouse.
A. THE KEYBOARD.
A keyboard is an input device that sends data in a
form of text and instructions to the computer.
There are various types of keyboards with varying
layout designs.
LAYOUT
Layout refers to how the individual keys on the
keyboard have been arranged. Some of the popular
kinds are
 QWERTY Layout
 Dvorak Layout
 Colemak Layout
The most commonest layout is the QWERTY layout.
THE QWERTY layout
This keyboard layout was designed in the
typewriter age. The primary concern at the
time of design was to ensure that the most
frequently used keys were separated so that
the mechanical arms of the typewriter keys
did not get in each other’s way. Most
computer makers adopted this layout.
THE QWERTY Keyboard Layout
Dvorak layout
This Dvorak layout was developed in 1936 as
an alternative to the dominant QWERTY
layout. This layout is to ensure speed,
accuracy and ease of use.
THE Dvorak Keyboard Layout
Colemak Layout
This Colemak layout came out in January of
2006 to be much easier to use and more
appealing to people who are already
accustomed to the QWERTY layout.
THE Colemak Keyboard Layout
The QWERTY layout was designed in the 19th
century to allow typewriter salesmen to easily
type the word "typewriter" and to prevent
typebars from sticking. We've been stuck with
QWERTY ever since.
Colemak is a modern alternative to the QWERTY
and Dvorak layouts. It is designed for efficient and
ergonomic touch typing in English.
Learning Colemak is a one-time investment that
will allow you to enjoy faster and pain-free typing
for the rest of your life. Colemak is now the 3rd
most popular keyboard layout for touch typing in
English, after QWERTY and Dvorak.
B. THE MOUSE
The mouse is an input device that enables the
user to communicate with the computer
through selecting, pointing to objects and
executing commands on the screen. It has an
arrow on the screen that corresponds with
movement of the mouse. The most common
types of mouse are
 The Mechanical Mouse
 The Optical Mouse
 The Laser Mouse
PARTS OF AN ELECTRONIC MOUSE
How to position
your hand on the
mouse.
The Mechanical Mouse
The mechanical was the first widely
produced mouse to accompany computers.
This type of mouse uses a ball which can
turn any in direction. As the ball turns, it
moves rollers (2, 3 & 4) that are attached to
the ball and this movement is turned into
electronic signals (5) that determine where
the mouse pointer on the screen should be.
MECHANICAL MOUSE
Optical Mouse
The optical mouse uses light emitting diodes
to detect change on the surface as you move
the mouse. The changes that these diodes
detect results in the movement of the pointer
on the screen.
OPTICAL MICE
Laser Mouse
The laser mouse is an improvement over the
optical mouse. The main difference is that
this mouse uses infrared laser instead of light
emitting diodes(LED). This has resulted in
the surface it is projecting on, hence
improving (laser eye) the pointer movement
on the screen.
LASER MOUSE
SYSTEM UNIT
The system unit is a box that contains most
of the electronic and electrical components
of a personal computer. The system unit is
usually made of metals (there are also plastic
types), and contains components such as the
central processing unit (CPU), motherboard,
memory, disk drives, hard disk and video and
network cards.
SYSTEM UNIT (TOWER CASE)
PARTS AND FUNCTIONS OF THE SYSTEM UNIT
The front view of the system unit is similar to the front panel
of the audio stereo system.
FRONTVIEW OF THE SYSTEM UNIT
Power button
To turn the computer on.
Reset button
Restating the computer, instructs the computer to go through the
process of shutting down, which would clear the memory and reset
devices to their initialized state. It simply removes power
immediately.
Motherboard
Main circuit board of the system unit, it has some electronic
components attached to it.
Power Supply
Converts standard electrical power into a form that, the computer
can use. If a power supply is not providing the necessary power,
the computer will not function properly.
DVD-ROM drive
A device that reads DVD-ROM, audio CDs, CD-ROMSs, CD-Rs
and CD-RWs.
CD-ROM drive
A device that reads audio CDs, CD-ROMs, CD-Rs and CD-RWs.
DVD/CD-RW drive
A combination drive that reads DVD and CD media, and writes to
CD-RW media.
Zip drive
A high-capacity disk drive that reads from and writes on a Zip disk.
Floppy drive
A device that reads from and writes on a floppy disk
Hard disk drive
A Type of storage device that contains one or more inflexible,
circular platters that store data, instructions and information
THE BACK VIEW OF THE SYSTEM UNIT
The back of the system unit has several sockets or ports
through which all peripherals are connected. The parts
include:
A. Parallel port
H. Power output
B. Cooling fan
I. Keyboard Port
C. Power input
J. Audio-speakers
D. Serial keyboard
K. USB port
E. audio-microphone
L. Blank plate (Expansion)
F. Monitor port
G. Serial prot
BACKVIEW OF THE SYSTEM UNIT
Here are some common hardware components
that you’ll find inside a system unit:

Motherboard

Central Processing Unit (CPU)

Random Access Memory (RAM)

Power Supply

Video Card

Hard Drive

Optical Drive (i.e. BD/DVD/CD drive)

Sound Card

Network Interface Card (NIC)

Analog Modem

FireWire/USB Expansion Card
TYPES OF PORTS
LAN Port
Standard Computer Parallel Port
USB Port
Standard Serial Port
Audio ports
TYPES OF CARDS, CONNECTORS & SLOTS
PS/2 Ports
USB Flash Drive
Power cable
VGA cable
USB Connectors
VGA Port (Monitor)
Firewire Cable
Network Card
A network card is an
expansion card that allows
computers to communicate
over a computer network.
Graphics Card
A video card (also
known as graphics
card) is an expansion
card whose function
is to generate and
output images to a
display.
PCI Slots
PCI (Peripheral Component Interconnect)
Typical PCI cards used in PCs
include: network cards, sound
cards, modems, extra ports such as
USB or serial, TV tuner cards and
disk controllers
Sound Card
A sound card is an
expansion card
that facilitates the
input and output of
audio signals
to/from a computer
under control of
computer
programs.
A. Central Processing Unit(CPU).
The central processing unit is the main
device that controls and process all the data
that is fed into the computer. Because of it’s
importance, it is sometimes referred to as the
‘brain of the computer’. In fact many people
refer to the system unit as the CPU. The CPU,
however, is only a component in the system
unit. CPU can also be referred to as
Microprocessor.
CENTRAL PROCESSING UNIT (CPU)
Microprocessor
B. Motherboard.
The motherboard is the main circuit board in
the system unit. This board serves as the base
connector which all other components of the
computer sits. Important devices such as the
CPU, the memory and the hard disk all
connect to each other via the motherboard.
The motherboard also has external
connectors that allow for peripheral devices
like the printer and speakers to be attached
to it.
MOTHERBOARD
C. Memory
Another important component in the system
unit is the internal memory. Memory is made
up of electronic components that hold
instructions and data that computer needs to
perform tasks.
MEMORY
D. Hard Disk Drive.
The hard disk drive(HDD) is a permanent
storage device in the system unit. This drive
stores data in electronic form on a magnetic
platter. The hard disk is the main storage
device on the computer and all the programs
installed on the computer resides on this disk.
Data stored on the HDD is permanent.
STORAGE DEVICES
The device of the computer that help us store
information and data are referred to as storage
devices. Storage devices come in many forms and
shapes.
Storage devices can be grouped based on how it
stores its data. Some storage devices use
magnetism (usually these types of storage are
called disk, spelt with letter ‘k’) to store data,
others use laser to write and read the
data(usually called disc, spelt with the letter ‘C’)
and some use electronic circuits to store the data,
referred to as flash memory.
TYPES OF STORAGE DEVICES .
By far the common types of storage devices
are:
External Hard Disk Drive
Optical Drive
Floppy Drive
Pen/Flash Drive
A. External Hard Disk.
The external hard disk drive is essentially the
same as the internal hard disk in the system
unit. This type of drive is not in the system
unit and is usually connected to the
computer using a universal serial bus (USB)
port. They are mainly used as backup drive
and such are used to store a second copy of
information already on the computer’s
internal hard disk drive.
EXTERNAL HARD DISK DRIVES
B. Optical Disc.
Optical disc drives are storage devices
that make use of laser beams to write to
and read from the storage media.
Optical disc comes in different formats,
but the most common format is the
compact disc.
Some examples of optical disc format
are;
1. Disc – Read Only Memory (CD-ROM).
The CD-ROM is the most popular optical
drive. This type of disc contain data that is
recorded at the of manufacture, and cannot
be erased or altered. Most music that we
buy are recorded on this type of format.
2. Compact Disc Recordable(CD-R)
This type of optical disc is blank when
bought. It can be recorded on once and
whatever has been put on the disc cannot be
erased. CD-Rs are best for writing data that
you intend to keep permanently.
3. Compact Disc Rewritable (CD-RW)
Like the name suggests, CD-RWs are disc
that can be written to and erased over and
over again. These discs require a special
reading device that is able to erase and write
new material onto the disk.
4.Digital Versatile Disc(DVD)
Digital Versatile Discs(sometimes also
referred to as digital video disc) have the
same dimensions as a regular CD. These disks
have a much bigger capacity and lowest (in
terms of capacity) of them can still store
more that six times the amount of data that
CDs take. DVDs also have the same
variations as CDs. Such as DVD-R, & DVDRW.
DVD-ROM
DVD-ROM DRIVE
C. FLOPPY DISK
Floppy disks are portable removable media
that uses magnetism to store data for future
use. They are sometimes referred to as
Diskettes of Disks.
D. PEN/FLASH DRIVE
A pen/flash drive is a memory storage device
that has a USB connector and can be
attached to a computer. The pen drive is
removable and portable and can be carried
everywhere. This type of storage has become
extremely popular because it is more
durable, lighter, stores more data and more
durable because they don’t have any movable
parts.
FLASH DRIVES
OUTPUT DEVICES
Output devices are the parts of the computer
system that sends signals from the computer
to the user. The output devices render
computer signals into a form that can be
understood by the human user. The most
common output devices are;
A. The Visual Display Unit(Monitor)
B. The Loud Speakers
C. The Printer
OUTPUT DEVICES
A. The Visual Display Unit (MONITOR)
The monitor is one of the most popular
computer parts. It displays what ever goes on
in the computer for the user to see.
There are two main types of computer
monitors. These are the Cathode Ray
Tube(CRT) and Flat Panel types.
 Cathode Ray Tube(CRT).
The Cathode Ray Tube is a type of display
unit that uses glass and electrons to project
images onto a screen. Because of the
complexity of creating images, the CRT has a
lot of parts and bulky and heavy in nature.
They are also cheaper than other types
display. They consume a lot of electricity.
 Flat Panel
Flat panel displays are modern ultra thin
visual display unit that use thin glasses and
special liquids to display the desired image.
Comparatively flat panel displays are more
expensive than CRTs and their images are
superior. They emit less radiation than CRTs
and consume less electricity.
B. Loud Speakers
Personal computers are also able to output
sound. Computer loudspeakers are the
output device that allows the sound to be
heard. They output sound. They range from
regular, small size computer loudspeakers to
surround system speakers with a subwoofer.
C. Printer
The printer is an output device that allows a
user to make a hard copy of a document that
has been created in electronic form. Printers
perform this task by making an imprint of
characters or symbols on media such as a
papers or a transparency. Most printers are
attached to the computer by a cable. The
main types of printers in use are impact
printers and non-impact printers.
DIFFERENT TYPES OF PRINTERS
Daisy Wheel Printer
Inkjet Printer
Dot Matrix Printer
Laser Printer
Impact Printers
Impact printers work in the same way as an
ordinary typewriter. The images or
characters are formed by a mechanism that
hits a ribbon against the paper leaving an
imprint. Impact printers are generally slow
and are not suitable for printing heavy
documents. They are very noisy because they
hit to make imprint. Examples of impact
printers are the daisy wheel and the dot
matrix printers.
Dot-matrix Printer
This is the oldest type of
printers. This printer operates
by having its pin strike against
the ink ribbon. The print out
from dot matrix is easily
recognized because of the
obvious lines and dots that
you can see on the image or
character it prints.
Daisy Wheel Printer
IMPACT PRINTERS
Non-impact Printers
The heads of non-impact printers do make
physical contact with the paper to print
images. These type of printers are generally
faster and quieter than impact printers.
Examples of non-impact printers are inkjet
printers, laser printers and thermal printers.
Ink jet Printer
Before the advent of laser printers, ink jet printers were
the most widely used printer type. They are cheaper than
any other printer types and produces quality output.
However, the only disadvantage is that the printing time
would take longer. It is because such kind of printers uses
variably-sized droplets of ink that is propelled onto the
paper or various print media.
Laser Printer
Laser printers are
faster than inkjet
printers. Laser
printers use laser to
heat and apply the
toner to specific parts
of a paper to form the
images . They work
the same way as
photocopiers. b
Plotters Printer
This type of
printer is ideal for
printing larger
drawings. This is
the most unique
printer so far
invented and
available in the
market.
PERIPHERAL DEVICE
Peripherals are pieces of computer hardware that
are added to a host computer in order to expand
its abilities. Most of those devices are optional in
nature.
External hardware devices attached to the
computer are called peripheral..
There are three types of peripheral devices:
a Input devices
b Output devices
c Storage devices
Examples of Peripheral devices
INPUT
DEVICES
OUTPUT
DEVICES
STORAGE
DEVICES
Scanner
Microphone
Webcam
Joystick
Light pen
Digital Camera
Printer
Plotter
Projector
Loud speaker
Headset
CD-ROM
Flash Memory
Flash drive
Zip Disk
Smart Chip
External hard
drive
Memory stick
Digital Video
Camera
Peripheral devices and their functions
Scanner
Barcode scanner
Scanner converts
images, print text
and handwriting
into digital form.
Handheld scanner
Sheet fed scanner
Webcam
A webcam is any video
camera that displays its
output on a web page.
LCD projector is a type
of video projector for
displaying video,
images or computer
data on a
screen
Digital cameras are
electronic devices
used to capture
and store
photographs
digitally.
CCTV CANMERA
A Closed-Circuit Television
(CCTV) video camera is a type
of digital video camera that
enables a home or small
business user to capture
video and still images.
A digital video camera allows you
to record full motion and store
the captured motion digitally.
The headphone is a pair of
small speakers placed over
the ears and plugged into a
port on the sound card to
generate sound.
A pair of speakers is
an audio output
device that
generates sound
A woofer or subwoofer
is used to boost the
low bass sound and is
connected to the port
on the sound card.
THE PERSONAL COMPUTER SOFTWARE
SOFTWARE
Software is a collection of computer programs,
procedures and documentation that performs
different tasks on a computer system.
Software contains the instructions that tell the
computer hardware what to do and how to process
data into useful information. Software refers to all
computer programs.
A program contains instructions or commands to
perform a task.
There are different types of computer software. The
major categories are the system software and
application software.
CATEGORIES OF SOFTWARE
Software can be divided into two categories, which are:
1. System Software controls and manage computer devices
and operations.
2. Application Software is used to perform a task and solve
a problem.
System Software
System software is responsible for controlling, integrating,
and managing the individual hardware components of a
computer system so that other software and the users of the
system see it as a functional unit without having to be
concerned with the low-level details such as transferring
data from memory to disk, or rendering text onto a display.
Generally, system software consists of an operating system
and some fundamental utilities such as disk formatters, file
managers, display managers, text editors, user authentication
(login) and management tools, and networking and device
control software.
There are three type of software under system software:
Operating Systems, Language & Language Processors and
Utilities
Operating Systems
An operating system (OS) is a set of software that
manages computer hardware resources and
provides common services for computer programs.
Operating systems perform basic tasks, such as
recognizing input from the keyboard, sending
output to the display screen, keeping track of files
and directories on the disk, and controlling
peripheral devices such as disk drives and printers.
For PCs, the most popular operating systems are
DOS, OS/2, and Microsoft Windows(XP and Vista),
but others are available, such as Linux(RedHat and
Ubuntu), Macintosh OS(Mac OS), and Unix.
Uses of Operating Systems
Operating systems are extremely vital for any
computer to function. Without operating
systems, computer hardware will not be able to
execute the instructions given to it.
Some specific uses are
1. Transfer of data from memory to disc
2. Translation of instructions into a format
that computer hardware will understand.
3. Monitoring and tuning up hardware
devices.
4. Allowing for multitasking at the same time.
Interface of most popular operating system
Windows Vista OS (interface)
Windows XP OS (interface)
Ubuntu, a Linux OS (interface)
The current Windows 8.1 OS (interface)
The current Windows 8.1 brings back the start button
Utility Software
Utility software is system software designed to help
analyze, configure, optimize or maintain a
computer.
Utility software is often targeted at technical people
with an advanced level of computer knowledge.
Examples of utility software are Anti-virus utilities,
Backup utilities, Data compression utilities , Disk
defragmenters, Disk cleaner, File managers,
Network utilities, Screensavers, Archive utilities and
Disk partitions.
Operating System
Anti-Virus Utilities
Application Software
Application software is used to accomplish
specific tasks other than just running the
computer system. The task that are
performed by application software include
accounting, typing, drawing, browsing the
internet, gaming, playing music and watching
video and so on.
There are two types of application software:
 Custom-made Software
 Packaged Software
Custom-made Software
Custom-made Software is an application
software that is specifically designed for
a particular customer to meet a specific
need. This type of software cannot be
bought from any shop. Usually the
customer will place an order for the
software
Packaged Software
Packaged Software is designed to be sold to
the general public. Many software houses
study the general requirement of computer
users and develop software packages.
Software packages are aimed at solving some
common problems such as word-processing,
spreadsheet calculation, database
management, presentation systems and so
on.
Examples of packaged software




Microsoft Office Suite,
Lotus Suite,
Open Office Suite,
Adobe Creative Suite etc.
Categories of packaged software:
Word Processing Systems – MS Word, Lotus Write,
WordPerfect
Spreadsheet Systems – MS Excel, Lotus 123,
Database Management Systems – MS Access, MySQL,
Oracle, MS SQL Server
Presentation Systems – MS PowerPoint
Graphic Designing – Adobe Photoshop, CorelDraw
Web Browsers – Internet Explorer, Firefox, Google
Chrome
Email Clients – Microsoft Outlook, Eudora Pro
Multimedia and Entertainment –Windows Media Player,
xDiv DVD Player, VLC Player, and computer games
Word Processing software used for creating textbased documents such as letters, reports, newsletters,
etc. A common example is the Microsoft Word.
Microsoft Word 2007
Spreadsheet software used for creating numericbased documents and charts such as financial budget,
students’ continuous assessments. A common
example is Microsoft Excel.
Microsoft Excel
Database software used for storing, sorting, and
retrieving large amount of data. This type of software
is used in banks and shops for storing information. A
common example is Microsoft Access.
Microsoft Access
Painting and Graphics software contains tools used to
draw and design posters, calendars, etc. A common
example is Microsoft Paint.
Microsoft Paint
Media Player software is used for playing sounds and
watching videos. Other common Media Player
software includes VLC, WinDVD, Musicmatch and
Power DVD.
Windows Media Player Application
Game software can be used to play different kinds of
games. These games come in a form of application
software. Example of computer games include
Solitaire, Pinball, FIFA 08, Scrabble, Chess, etc.
FIFA 08 computer game
A Computer Chess game
Microsoft has a software package that contains
several application software called the Microsoft
Office Suite. This includes Microsoft Word, Excel,
PowerPoint, Access, Publisher and Outlook.
Microsoft Office Suite
COMPUTER VIRUSES
DEFINITION:
• Computer viruses are malicious code written
by individuals with the sole aim of disrupting
the normal and smooth operations of the
software of a computer.
The viruses may multiply in your computer, most especially, at
the storage devices example, memory, hard disk, floppy disk and
compact disk (CD
Computer Viruses
TYPES OF COMPUTER VIRUSES
Computer viruses can be classified into several different types.
1.
2.
3.
4.
5.
6.
File infecting or Program Viruses:
It infects program files with extensions like .EXE, .COM, .BIN, .DRV and
.SYS. Some file viruses just replicate while others destroy the program
being used at that time.
Boot Sector Virus:
This infect the master boot record of the hard disk or the floppy drive.
Multipartite Virus:
They infect both files and boot sector of the computer system.
Stealth Viruses:
They are stealth in native and use various methods to hide themselves
and to avoid detection.
Polymorphic Viruses:
They are the most difficult virus detect
Macro Viruses:
A macro is an executable program embedded in a word processing
documents or other type of file
DIAGRAM OF TYPES OF COMPUTER VIRUS
Sources of computer viruses
The top sources of virus attacks are highlighted below:
• Downloadable Programs
• Cracked Software
• Email Attachments
• Internet
• Booting From CD
Downloadable Programs
One of the possible sources of virus attacks is
downloadable programs from the web. Unreliable
sources and internet newsgroups are one of the main
sources of computer virus attacks.
Cracked Software
Most people who download cracked and illegal versions
of software online are unaware about the reality that
they may contain virus sources as well. Such cracked
forms of illegal files contain viruses and bugs that are
difficult to detect as well as to remove.
Cracked Computer Software
Email Attachments
Email attachments are one of the other popular
sources of computer virus attacks. There exists a
possibility that senders of e-mail unknowingly forward
virus along with the email attachment.
Internet-Best Possible Source of Viruses
E-mail Icons
Internet-Best Possible Source of Viruses
Since the internet is a world wide interconnection of
computers viruses spread over here quickly.
Downloading software from the internet is an easy way
to transfer virus.
Internet Pages
Removable Storage Media
Storage media such as floppy disks, CDs, external hard
disk and USB storage devices can carry viruses when
used on computers that are already infected.
Removable Storage Media
Network
Computers connected to each other on a network can
spread virus quickly when on computer if infected.
Computer Networks
PROBLEMS OF COMPUTER VIRUSES
 they are not easy to remove.
 they are destructive and obstructive programs.
 they replicate themselves, spread themselves and
some even disguise as a real program.
Symptoms
Speed: your computer system may slow down
under the influence of viruses as they consume
your system memory for their execution. This
means that virus only execute with the help of
system memory like RAM (random access
memory).
Operation: computer may hang frequently of
may display errortic error messages, viruses are
capable of colliding two program together (eg
Microsoft Word and Corel Draw), thereby
creating software (program) conflict making the
system to hang.
Booting: your computer may suddenly restart at
times, may not load properly, in few experience,
you may not be able to access your disk drives.
Peripherals: some computer viruses may invade
your Device Manager.
EFFECTS OF VIRUS ON COMPUTERS
 Slows Down Computers
Virus slows down computer since it uses the
computer’s memory whilst active.
 Loss of Data
Some Viruses corrupt data and render them useless
such that that data may have to discarded.
 Data Theft
Some type of computer virus such as spyware can steal
data and pass it on to a dangerous hands.
 System Crash
Computer virus can also lead to a total the total carsh
of a computer. In some extreme situations, the
computer may refuse to boot properly.
PRECAUTION AGAINST VIRUSES
1. Avoid copying infected files
2. Desist from images and folder sharing, because it
may contain virus
3. Update your antivirus software every month avoid
pirating software's
4. Avoid printer sharing
5. Scan any storage device such as flash drive before
making use of it
6. Avoid online downloading and internet sharing.
7. Install active antivirus software
8. Avoid networking and pairing of devices
9. Avoid files transfer through Bluetooth, infrared or
USB
PROGRAMS THAT PREVENT COMPUTER
VIRUSES
Antivirus program
Antivirus programs are written to ensure that a
computer is protected from viruses and not
infected with virus. Hence it is the most effective
and major defense against virus. Examples are:
McAfee Virus Scan
Avast Antivirus
Norton AntiVirus
Kaspersky AntiVirus
Avira AntiVirus
AVG Antivirus