HELP DESK
Computer Studies
FOR
JUNIOR SECONDARY
Veman Samuel
Chongo Borniface
Lungu Mathews
Computer Studies
Design and Technology
Computer Studies
First Edition
Table of Contents
Preface.....................................................................................................................................................ii
UNIT ONE .............................................................................................................................................. 1
INTRODUCTIONS ............................................................................................................................ 1
What you can do with the computer......................................................................................... 4
Importance of learning computer studies ................................................................................... 6
Dangers of using computers ......................................................................................................... 7
Troubleshooting ............................................................................................................................ 9
UNIT TWO ........................................................................................................................................... 11
HARDWARE UNIT ......................................................................................................................... 11
Computer parts .............................................................................................................................. 11
Household appliances with microprocessors ................................................................................ 20
UNIT THREE ....................................................................................................................................... 26
SOFTWARE ..................................................................................................................................... 26
Software unit ................................................................................................................................. 26
TYPES OF SOFTWARE .............................................................................................................. 27
UNIT FOUR ......................................................................................................................................... 31
PRODUCTIVITY TOOLS ............................................................................................................... 31
WORD PROCESSOR .................................................................................................................. 31
SPREADSHEET ........................................................................................................................... 41
POWERPOINT ............................................................................................................................. 58
UNIT FIVE ........................................................................................................................................... 68
NETWORK....................................................................................................................................... 68
Network......................................................................................................................................... 68
Internet .......................................................................................................................................... 74
i
Preface
This book is published to respond to the increased need of computer studies improvement
in Zambia. Simple language and terminologies were used to provide simple comprehension
of computer studies content.
Computer studies help Desk directly answers the requirement of the examinations council
of Zambia in grade 9.
ii
Introduction to Computer
UNIT ONE
INTRODUCTIONS
Learners should be able to;
-
Define a computer
Classify computers according to their capacities and speed.
Understand the application of computers in basic social institutions.
Many people nowadays are using computers for them to perform various tasks in their
respective day to day activities. There are thousands of computer programs or applications
which can be used to perform those different tasks. As a computer user, you can choose a
number of programs which may best suit what you would like to do with the computer.
What is a computer?
A computer is a programmable-electronic machine which inputs, stores and processes data
and outputs information. A computer allows a user to put in (input) data in the computer
systems. The data in the computer system is then processed or changed into information.
Information is later put out (output) of the
computer system.
Information and data
Think about:
A computer follows exact commands you give to
it in form of data, and then later, it responds back
to you in form of information. Data is
unprocessed information. Humans cannot easily
make sense of data.
Data is unprocessed information while
information is processed data.
Simple example 1: Imagine, you have a young
sister aged 6 named Carol. One morning she
wakes up from sleep and just says, “3”. You will
ask her questions about that number she just
said. Like…..
010101010101010101010010010101
This is an example of data. It is hard to
make sense out of it.
While---
This is an example of information.
It is easy to make sense out it.
1. Are you dreaming?
2. Why did you say 3?
This is because just saying „3‟ it can mean anything. It can mean 3 apples, 3 mangoes, 3 years
old, or any other 3 things. And it doesn‟t make sense to the mind of someone listening. If the
child later says “I meant, I am 3 years old today,” now that is information. Information is
when data makes sense to the human mind.
1
Computer data is expressed in binary digits (zeroes and ones). Humans can easily
understand data when it is changed to information by a computer. Information is processed
data. However, data is packed into groups of instructions called files. So a computer needs
to process data in order to be useful to humans.
TYPES OF MULTIMEDIA FILES
-
Audio files – audio files contain sound wave data or information. For example of
audio file is media player 3 (mp3)
Text files – text files contain data or information letter, numbers and symbols.
Forexample .txt, doc, and .xlsx.
Graphical files – graphical files contain picture data or information. For example
png, img, jpeg, bitmap and thumbnails.
Video files – video data or information contain videos. Such as Media player 4 (MP4)
and GIF.
Types of computers
Mainly computers are grouped based on the amount of data or instructions they can process
per second.
a) Supercomputers
A Supercomputer was firstly developed by Roger Cray in 1976. It was designed to
handle huge amount of data. It contains thousands of connected processors.
Therefore, it can process trillion of instructions per second. This makes it the fastest
and largest type of computers in the world today.
Use:
Supercomputers are used in scientific and engineering applications such as weather
forecasting, nuclear energy research and scientific simulations (space exploration).
b) Mainframe computers.
Mainframe computers are designed to support hundred and
thousands of different programs at a time. This is called multitasking. It allows multiple users to use one mainframe
computer. This makes them fit to be used in big organizations
such as banks, telecommunication companies, and online
businesses which handle large numbers of users and data.
Mainframe computers are used as workstations and servers.
c) Minicomputers
A minicomputer is a medium sized multiprocessing computer. This type of
computers supports 4 to 200 users at a time. They are smaller than mainframes
2
computers. They are used institutions or departments for different works like billing,
inventory management and accounting.
d) Personal computer (PC)
It is known as a microcomputer. It is designed for personal use. It
consists of a microprocessor as a central processing unit (CPU),
input unit, storage unit, and output unit. This type of computers
is suitable for personal work, such typing school work, watching
movies, playing music or storing pictures.
Personal computers are largely used for office work such as laptops and desktop
computers. Through this book, we will largely focus on personal computer (desktop
computer)
The diagram below shows the summary of the types of computers.
Type
Supercomputers
Mainframe computers
Minicomputers
Capabilities
Characteristics
Handles Large - Very fast and
amount
of
large
instructions per - Handles
very
second.
large
amount
instructions per
second
Can be operated - Very fast but not
by
Hundred
compared
to
thousands
of
supercomputers
user a at a time.
- Supports many
It
supports
users at a time.
thousands
of - Processes
large
instructions at a
amount
of
time.
instructions but
not compared to
supercomputers.
Supports 4 to 200 A minicomputer is a
users at a time.
medium
sized
multiprocessing
computer. This type
of
computers
supports 4 to 200
users at a time. They
are smaller than
3
Application
- Used in scientific
and
engineering
applications.
Used
in
big
organizations such as
banks,
telecommunication
companies and others
to process bulk of
users data.
Used institutions or
departments
for
different works like
billing,
inventory
management
and
accounting.
Personal Computers
It contains a
single processor.
So, it has the
least processing
speed of all the
types
of
computer
mainframes
computers
It consists of a
microprocessor as a
central
processing
unit (CPU), input
unit, storage unit,
and output unit.
Suitable for personal
work, such typing
school
works,
watching
movies,
playing
music
or
storing pictures.
What you can do with the computer
Before we discuss about the importance of learning computer studies, we will discuss about
various tasks you are able to do using a computer.
What I can do with a computer.
Create word document.
A computer allows you to type edit and print words. However, by doing so, you can type,
edit and print a letter to you mother, father or friend. In general, you do anything that
involving writing information. Some of the following content you can type using the
computer are;
- Books
- Any form of a letter
- Autographs
- Biography
Create graphical designs
A computer has special applications (apps) it works with to create and print beautiful
graphical designs such as birthday cards, banners, posters, billboards, certificates, flyers,
business cards, calendars and brochures.
This means that using a computer you can design your own wedding card or your own
calendar.
Browsing
Information about your school work today is totally found on the internet. Using a
computer, you will use special browsing applications such as internet explorer, Google
Chrome, Mozhila firefox, Opera Mini and Pheonix. Searching using these website
4
applications, you can find enough information about your school work. To search for
information on the internet is sometimes called internet surfing.
Information sharing
One of the most important functions of a computer is its ability to connect with other
thousand computers in the world using signals. This connection makes it easier for people
to share information within the same area or across workplaces, homes, countries or
continents.
Stores information
Computers have been built in a way that
information is stored in files in the computer
memory. Some computers hold a large amount of
files.
Computers use the database management systems called file management that uses tables
to store information, sometimes called relational. Schools nowadays are using computers to
keep all their school records.
Create websites and gaming applications.
Websites are used to give more information about a particular person, company or area.
When you use your mobile phone to search on Google, it will provide you with a number of
websites to visit. Some of the most visited websites are;
- Facebook
- Twitter
- Instagram
- Paypal and many others.
Using a computer, you eventually learn how to create those websites.
Gaming applications are created using computers. Equally studying how a computer works
and how to use, eventually you will learn how to create gaming applications. Most common
gaming applications played by young people today are;
Fifa football game
Mortal Kombat
Activity
1. In half a page, describe how you can use a computer to help your parents to organize
a family summer vacation out of town.
5
Importance of learning computer studies
The following are key importance of learning computer studies.
-
-
-
-
Computer application makes it easy to solve daily problems
Learning computer studies you will learn how we can use a computer to solve
everyday challenges.
There are so many challenges today in homes, industries, markets, and big
institutions that can be solved by the use of computers.
o Computers in homes
Computers are used for keeping records at home such as creating and keeping
a list of groceries to buy.
o Computers in industries
Industries that manufacture dangerous materials such as fertilizers where
people can be sick work near them, machines that are connected to the
computers are used to control the works in dangerous areas of the industry.
Industries are different and all produce different products. Nevertheless, all
use computers to control what they produce.
o Computers in market.
Selling and buying things (goods) have been very hard especially over a
distance. However, using computers, people can buy and sell their products or
goods to people around the world. This is called e-commerce or online market.
o Computers in big institutions
Small and big institutions use computers to organize their work in a nice
order. In these institutions, managers use computers to keep records of
workers, goods and services they provide and the details of their clients.
Computers a capital to get a job
When you learn to work with basic computer software such as Microsoft word, excel,
publisher, PowerPoint and access, this means that you can be employed at a
company to create various materials using a computer.
Computers can save paper.
As you may know that paper that we use to make books, boxes and plain papers are
made from trees, one reason why trees are cut is to make paper out of them. This is
causing a lot of trees to be cut. When we use computers to make materials that can be
ready on the computer such as eBooks, eReceipts, eQuestions and many more others.
So, there is no much need to print information on papers.
Computers promote innovations and creativity
Young children are learning how to use computers to create cartoons, and games on
a computer. This is the sign that computers are promoting innovations amongst the
6
young people. You can generate money by creating websites that allows people to
buy goods using a computer.
- Computers help communication
The use computers helps people to communicate with people
who are both near and far. Long time ago, we use to
communicate using letters. It used to take months to get the
response. But now, we can communicate with our relatives who
live miles away from us and keep getting their response within seconds. Today
computers allow us to see each other with our relatives using videoconference, and
we can share pictures using platforms such as Skype, Facebook, WhatsApp and
others.
- Computers help us to learn a lot about the world.
Computers have become the window to see the world. Through computers, we can
get the information about every place in the world. Computers can connect to the
internet and search for anything we want, and the answer will be given.
Activity
1. List four importance of learning computer studies.
2. Explain why computers help communication.
Dangers of using computers
Although computers are very good and nice to use, they have very big bad impact to our
lives. Some of these impacts are;
1. Repetitive Strain Injuries (RSI)
These are health problems likely to be caused by using a computer for a longer
period of time. When you sit on a chair for a longer period of time, you will be likely
to complain of your back, neck or eyes. Equally, working with computers you would
spend more hours sat in the same place. These injuries are made even worse by poor
working space. However the following are the common health related problems
caused by using computers.
a. Posture related injuries
Back, neck, shoulders and hands ache is commonly caused by your sitting
standards on your computer.
o Back and neck ache.
o Muscle and joint injuries.
Prevent posture related injuries
7
Use an adjustable chair and desk especially those
designed f or use with computers. This will help
prevent back and shoulders ache.
 Use ergonomic chairs. Ergonomic chairs hold
your spine in curve-like shape when you are
sitting.
 Have your computer screen or monitor at the level of
your eyes or slightly lower to help keep your neck in
right position.
b. Eye strains
Prevent eyestrains from computer use.
 Reduce the brightness of the light from your monitor or screen.
 Sit a bit distant from the computer monitor or screen.
 Have regular eye check up by medical experts to examine
c. Obesity – sitting in one place for a long period of time too often attracts a
condition called obesity.
2. Loss of privacy
Using the computer especially on internet leads to loss of privacy. A computer store
so much more information about your sensitive personal details. Malicious people
like hackers or scammers get your details, they may use them for illicit purposes such
theft.
To prevent loss of privacy
 Don‟t send confidential information of internet such as passwords,
PINs and Passcodes.
 Keep your programs on your computers up to date.
 Do not access unreliable websites.
 Be aware of phishing. Phishing is when malicious people pretend to be
a company such as a bank you have an account with and requests your
bank details in order to upgrade your account.
3. Computers can cause hazards
A computer is an electronic device. Most desktop computer use direct power from
the power source. However, power source cable can cause serious harm to the
computer user sometimes even death if the cable is not taken care of.

Activity 1
1. Define the following terms
a. Phishing
b. eCommerce
2. RSI stands for………………………………………………..
3. Give four reasons why computers should be handled with care.
8
i.
…………………………
ii.
…………………………
iii.
………………………..
iv.
…………………………
Troubleshooting
A computer is a beautiful device to use but, sometimes it develops faults that make it fail to
work normally. Some faults are miner but others are big such that they may need a
technician to work them out. Troubleshooting is the systematic processing of finding the
cause of a faulty in a computer system. Establishing a faulty in a computer system, you
must identify a specific problem before troubleshooting.
The table below shows some of the most common computer faults and how to troubleshoot.
Fault
Failure to turn on
General slowness
Peripherals not working
(mouse, keyboard or monitor)
Blue screen
Troubleshooting
Check if the power supply is reaching the
computer device. In many cases a power
cable has problems.
Check if the power switch at the back of
the desktop computer is turned on before
pushing the on/off button.
Turn the computer off and on. This will
allow the computer to start afresh and
close programs that were running.
If that does not work, check the remaining
storage space of your computer.
Check if the peripheral is connected to the
computer.
Most peripherals have indicators using
light to show connection. It a peripheral is
connected and is not working then, it has a
fault.
Blue screen is one of the most terrifying
faults that computers having software
faults show.
If the software causes a blue screen, let the
system turn off and reboot on its own.
Caution
Please note that:
1. Do not try to repair a computer that does not belong to you without the owner‟s
permission.
9
2. Do not try to troubleshoot computers in the laboratory without the permission from
the teacher.
3. To avoid further damage to the computer, do not open the CPU to repair. You can
contact your computer studies teacher.
Activity
1. Define troubleshooting.
2. Give two common computer faults
3. What would you do if a computer begins to respond slower?
10
INPUT, PROCESSOR, STORAGE AND OUTPUT DEVICES.
UNIT TWO
HARDWARE UNIT
Computer parts
A computer has two parts.
1. Hardware part
2. Software part
Hardware is a physical part of the computer system. It is the part of a computer system we
can touch and see. A computer is made up of a set of hardware components called units
which are connected to the central processing unit (CPU).
Hardware units.
There are four (4) hardware units of a computer system.
1.
2.
3.
4.
Input unit
Output unit.
Processing unit
Storage unit
Each unit has a group of devices. All devices in one unit perform similar tasks.
INPUT UNIT
An Input unit of a computer system has a group of devices which all are used to put
in data into the computer system. These devices are called input devices. Input
devices are connected to the computer for them to work with it. An input device is a
part of a computer system used to input data into the computer.
Examples of input devices
1. Pointing devices of a computer.
These are input devices used for controlling information on a computer. There are
two groups of pointing devices.
a) Mouse
This is the most common group of pointing devices on the computer system.
The Mouse pointing devices are used for selecting, scrolling through a
document or list, clicking and dragging information on a computer system.
i)
Mouse
A mouse is a pointing device which can be held by
hand and moved across the surface in order to
move the cursor in the computer system.
11
ii)
Touchpad
A touchpad or trackpad is a pointing device which has a sensor surface
that translates the motion and position of a user‟s finger to the
computer system. Touchpads are commonly attached to the laptops just
below the keyboard. Touchpads have now replaced computer mice in
portable laptops.
iii)
Joystick
A joystick is cursor controlling input device used in
computer gaming. Game controllers have two joysticks
used to direct movement of objects in a game.
Trackball
A trackerball is a pointing device consisting of a ball partly held in a
socket containing sensors to detect the rotation of the ball as the way of
controlling the cursor in the computer system. Trackerballs were used
in old mice. Today trackerballs have been replaced by infrared lights in
modern mice.
Scroll ball
iv)
v)
b) Pen
This group of mice is used for drawing on a computer system.
i)
Light pen
A light pen is a computer pointing device which is used to select,
display menu items or draw pictures and write on the monitor screens.
ii)
Stylus sometimes called pack
iii)
Computer pen
2. Keyboard (QWERTY)
A keyboard is a computer input device used to input
letters, symbols and numerical data into the computer.
A keyboard is made of number keys, letter keys,
function keys, escape key, arrow keys, space key,
space bar, numerical key pad and enter key.
3. Microphone
This is the device which inputs sound waves into the computer
system. A microphone changes the sound vibrations to computer
understandable form (binary). Sound waves are organized in a file
called an audio file. Audio data is sent from the microphone to the
computer using a connecting cable. Microphones are used for many
forms of communication such as musical, vocal and speech recording.
12
4. Scanner
A scanner is an input device which turns a hardcopy file into a computer. All
printable files in the computer are viewed as
softcopies. A soft copy is a printable file which can
be viewed and manipulated on a computer system.
All printed files which a viewed on a paper is called
hardcopy. A scanner is therefore viewed as an input
device because it captures a hardcopy file and sends
it into a computer system to be viewed as a softcopy.
Flatbed and handheld are commonly used types of scanners.
5. Magnetic stripe card reader
A magnetic stripe card reader is an input device
which reads input personal information on the
magnetic stripe card into a computer system. A
magnetic stripe card contains a black stripe
made of magnetic material which encodes
information of a card holder. A magnetic strip on a card is swiped through a
magnetic stripe card reader to scan the user or holder‟s personal information. A
magnetic stripe is used in encoding personal information on drivers‟ licenses,
automated teller machine (ATM) Card and National pension‟s schemes authority
(NAPSA) cards.
6. Smart Card reader
A smart card reader is an input device containing a microprocessor and memory
chip that stores personal
information. a smart card is
inserted into smart card
reader such as phone sim
card slot or Automated
Teller Machine to read the
information stored on it. A
subscriber identity module
(SIM) card and Automated
Teller Machine (ATM) card are good examples of smart cards.
7. Magnetic ink character recognition (MICR) reader
Magnetic ink character recognition is a device which scans, reads and input
characters printed using magnetic ink on a special paper into a computer system.
Magnetic ink character recognitions are commonly used in banks to scan, read
13
and input cheque details into a computer system. A bank cheque is filled in and
signed used a special pen containing magnetic ink. However, magnetic ink
character recognition like a flatbed scanner reads and inputs the information
printed on a cheque into computer system.
8. Optical Mark Recognition (OMR) reader.
An optical Mark recognition reader is an input device which uses a light beam to
scan marks on a special paper (sheet). A special paper (sheet) allows all the light
rays to fully pass through it. When a mark is placed on
any point of the sheet, it will stop the light beam to pass
through. This will send the information to the computer.
Optical Mark Recognition readers are used in education
to mark multiple choice questions by shading an answer
sheet using an HB or 2B pencil. In this case, an HB or 2B
pencil is to create dark marks on an answer sheet which the OMR reader will scan
and read.
9. Optical character Recognition (OCR) reader.
An optical character Recognition computer input device reads standard font-sized
typewritten or handwritten characters and input them into a computer. The
special typewritten standard font-size read by optical character recognition
readers are called OCR font. OCR devices are used to process utility bills such as
water, electricity and other home bills. OCR devices are also used to contain a
price code on products.
10. Barcode reader
A barcode reader is a handheld scanner which reads information on a printed
barcode. A barcode reader reads the information decoded in the barcode and
sends the information to a computer system. Barcode readers are used on Pointof- Sale (POS) and are commonly called price
scanners.
Uses
a. Since prices are stored in the barcode, barcode
Barcode reader
readers are used for fast and accurate checkouts in
busy shopping malls.
b. Using a barcode reader it is very easy to track the
flow of a business. A manager would tell how
many products have been sold on a particular day.
c. Barcodes are used protect sales against theft. If each product is barcoded, then
any theft will be identified.
Information decoded on a barcode
1. Product name
14
2. Product price
3. Product weight
4. Product‟s manufacturing and expiry date.
5. Name of the manufacturer.
11. Digital Camera
A digital camera is an input device which captures and
input images into a computer. A digital camera can also
capture and input videos into a computer system.
Modern digital cameras have a processor, monitor and
storage which allow images and videos to be processed,
viewed and stored within a camera. But that does not
stop a digital camera from being an input device. This is because its original
purpose is to capture and input images and videos into a computer system.
SUMMARY
Input unit consist of a group input devices which put in data into the computer
system. These input devices are;1. Pointing input devices
i)
Mouse
ii)
Joystick
iii)
Trackball
iv)
Light pen
v)
Stylus
vi)
Computer pen
2. Keyboard
3. Digital Camera
4. Scanner
5. Microphone
6. Barcode reader
7. Smart card
8. Optical mark Recognition reader
9. Optical character recognition
10. Magnetic stripe card reader
11. Magnetic ink character recognition (MICR)
Exercise
1. Which input device is used
gaming?........................
2. List two pointing input devices.
15
in
place
of
a
mouse
in
computer
3.
4.
5.
6.
7.
i)……………………………
ii)……………………………
A keyboard is used to input………………
Which of the following is used for capturing graphical data?
A. Camera
B. Keyboard
C. Mouse
D. Optical Character recognition
……………………is can be used to mark multiple choice tests.
Study the diagram below.
a. Name the feature shown above.
………………………………….
b. Give two institutions which use the feature shown above.
i.
…………………………………..
ii.
…………………………………..
c. State any two personal information stored in the feature shown above.
i.
……………………………..
ii.
……………………………….
Study the diagram below.
a. Name the feature shown above.
……………………………
b. Name a device used to scan information on the feature shown above.
……………………………………………
c. Name one use of the feature shown above.
………………………………………
d. List three kinds of information stored in the feature shown above.
i.
………………………………..
ii.
……………………………….
iii.
……………………………….
e. Give two advantages of using the feature shown above.
i.
…………………….
ii.
……………………….
8. Which of the following is not an ink and mark recognition reader?
A. Scanner
B. Optical Mark recognition
C. Magnetic ink Character recognition
D. Optical character recognition.
16
9. Which of the following input devices is used for drawing on a computer system?
A. Mouse
B. Joystick
C. Light pen
D. Trackerball.
10. Study the diagram below.
Plastic Card
Magnet coat
a. Name the input device which will be used to read the information shown on
the diagram?
…………………………………
b. Name one institution which uses the information shown in the diagram above.
……………………………………
c. Explain how the device you mentioned in (a) works.
………………………………………………………………….
……………………………………………………………………..
……………………………………………………………………..
1. Output unit
The output unit of the computer system is a set or group of devices used to put
information out of the computer system. However, these devices used to output
information called computer output devices.
Examples of output devices.
a) Monitor screen is an output device that output visual information to a user. This
means that computer users use the monitor screen.
b) Printer
A printer is an input device used to turn softcopy information to hard copy using
ink.
c) Speaker
d) Projector
17
INPUTTING AND OUTPUTTING MULTIMEDIA.
Each type of files is input or output by a specific group of computer peripherals. Look at the
table below.
Multimedia
Audio file
Text files
Input device
Microphone
Keyboard
Graphical files
Camera
Scanner
Video files
Camera
Output device
Speaker
Monitor
Printer
Projector
Printer
Monitor
Projector
Monitor
2. Processing unit
The central processing unit (CPU) is the center of all computer processes. Data from
input devices is put into CPU to be processed and later information is sent out from it
through the output devices. All computer devices which can be connected to the
central processing unit (CPU) are called peripherals.
The CPU is a set of internally enclosed electronic components which work together to
allow;
a) Data to be input in the computer system,
b) Data to be processed,
c) Data to be stored into the computer system and
d) Data to be output out of the computer system.
Internal parts of the computer system
1. Motherboard
The motherboard is an internal part of the computer system where data is
processed. It is embedded on it, a microchip. A microchip receives and processes
instructions given to it. It is sometimes called a microprocessor.
2. Cables
3. Uninterruptible power supply (UPS)
4. RAM
5. Hard drive
6. Fan
7. Video card
18
The parts mentioned above are all found inside the CPU housing. This means that,
for one see these components, he/she must open the central processing unit housing.
Processor
A processor is a small part of the computer system which processes data. Sometimes
a processor called a microprocessor. A processor has two main parts. These are;
1. Control unit
2. Arithmetic logic Unit
1. Control Unit.
The control unit is part of a computer processor that manages data in the
computer system. Every data input into the computer using input devices will
need to pass through the control unit so that each file of data can be named
and sent to be stored in the ROM.
Functions of the control unit
a. Manage data input into a computer system
To receive the incoming data
and pack them into files.
To name the files.
To send the files into the ROM.
To write the details of each files sent to the ROM. The following are
some of the details that are written down in the register.
 Name of the file
 Size of the file (E.g KB, MB or GB)
 Format of the file (e.g music.mp3, document.docx,
video.mp4, picture.img)
 Address number – a place
where that file will be stored
in a ROM.
A file where details all files are
written is called a register. The
processes of writing the details of the
files in the register is called registry.
-
The control unit keeps the register of all files stored in the ROM.
19
b. Assign connected computer peripherals to output information.
The control unit is responsible to assign or direct the information to the
right output device. This means that, if the music file is opened, the control
unit will assign the speaker to output it. Equally, if a user wants to print a
document file, the control unit will assign the printer that is connected to
the computer. The diagram below shows how the control unit assigns
connected peripheral to output information.
2. Arithmetic logic Unit (ALU)
The arithmetic Logic unit is a part of a processor that carryout mathematical
expressions and make decisions. The arithmetic logic unit makes simple
calculations such as addition, subtraction, multiplication, division, greater
than, equal to and less than.
a. Functions of the arithmetic logic unit.
To make mathematical operations such as addition (+), subtraction(-),
multiplication and division.
To perform logical operations. This means that the arithmetic logic unit
makes intelligent decisions when two or more options are presented.
The ALU uses greater
Household appliances with microprocessors
Most of the house appliances are embedded with microchips that controls the way they
work. Microprocessors help the appliances to manage time, temperature and information.
Below are some of the common household appliances that contain microprocessors
1. Washing machine
The microprocessor in a washing machine allows the right amount of water entering
the valves. It was makes sure the washing process goes through each stage correctly.
It gets the information from the temperature sensors and turns the machine on and
off.
2. Intelligent oven and Microwave
The microprocessor inside the intelligent ovens can read the barcodes on packaging
and then automatically set the temperature and cooking time to the perfect level.
3. Intelligent fridges
The microprocessor inside intelligent fridges is able to read the barcodes on the food
and determine the use by dates. Food that‟s about to go bad is moved in front of the
fridge so that can be used first.
4. Computer system
20
A microprocessor inside a computer, laptop or mobile phone controls all what goes
in the computer.
Other household appliances with microprocessors inside
1. Dishwasher
2. Electric kettle
3. Hairdresser
4. Remote control television
5. Burglar alarm system
Advantages of using household appliances with microprocessor inside
1. Increased productivity - Allow people to perform various tasks at the same time.
2. Increased relaxation - Give people enough free time.
3. Increased leisure time,
Disadvantages of using household appliances with microprocessors inside
1. Laziness – when devices do most of the work by themselves, people using them
become so lazy.
2. Decreased fitness – work gives us sort of fitness. However, if the devices are
doing all what we should be doing then, we will not be exercising through work.
STORAGE UNIT
A storage unit is made up computer devices used to store data. These devices are
called storage devices. Storage devices contain magnetic coats on them which allow
them to store data. the computer storage system can be grouped into two categories.
1. Primary memory
This is the first or internal set
of the storage devices of a
computer system. There are
two storage devices under
primary memory.
a) Random Access Memory
(RAM)
A RAM is a volatile
memory of a computer
system. This means that
data is stored temporary in
the RAM. A RAM can only store the data which is being processed. This
means that all programs running are store in a RAM. Once a program has
21
stopped running, it is removed from the RAM. Most RAMs have the
storage space of 2GB, 4GB and 8GB. The bigger the RAM storage space, the
more expensive, faster and efficient the computer is.
b) Read Only Memory (ROM)
This is the static or non-volatile memory of the computer system. This
means that data is stored in this memory permanently until it is deleted or
destroyed by viruses. A ROM is a where all programs and files are stored.
The control unit will fetch programs from the ROM and send them to RAM
to be ran or processed. When a program has stopped running, it is
removed from the RAM and sent back to the ROM. A hard drive is a good
example of a ROM. Most personal computers have an average of 350 – 500
GB storage space.
c) Cache Memory
A cache memory is the storage system which allows easy and fast access of
data. The cache memory lies just near the RAM.
The sense behind the Cache memory is that, those
most used programs are stored in the cache
memory so that it is fast to fetch them when
needed. So after a most used program has ran and
gets removed from the RAM, it is not sent back to
the ROM, however, it is sent to the cache memory.
so that when we need to use the program again, we
don‟t take time to fetch it from the ROM but just
get it from the Cache memory.
i)
Secondary memory
Secondary memory is an external alternative storage device of a computer
system used for storage backup. In the case when the storage space has
running out due to amounting number of files in the computer primary
memory (ROM), an external additional storage device is used to store extra
files. Therefore, those external additional storage system used to store extra
files when space in the ROM has run out is called secondary memory. Mostly
secondary memory hardware devices are used for storing and transporting
data. s
a) Flash drive sometimes called pen drive. When a computer‟s hard drive
runs out of space, one is likely to use a flash drive to store extra files. A
flash drive is sometimes used to carry files across computers.
b) Compact Disk (CD)
22
c) Floppy Disk
d) Magnetic Tape
e) Memory card
f) External hard drive.
The diagram below shows the classes of computer memory.
Class
Primary Memory
Secondary Memory
Definition
This is the first or internal
set of the storage devices of
a computer system.
external additional storage
system used to store extra
files when space of the
ROM has run out
Example
- RAM
- ROM
-
Flash drive
Compact Disk
Memory Card
Floppy disk
Magnetic Tape
Binary digits
A computer system is able process data in binary numbers. For a computer to
understand instructions (data) we input into it, every instruction must be expressed
in base 2.
Changing numbers to base 2
In this example we will change the following numbers to base 2
i)
710
2
7
R
3
1
0
0
1
1
1
0
01112
ii)
1210
2
12
R
6
3
1
0
0
0
1
1
11002
23
From the examples above, it means that 7 can be understood by a computer if it is
presented as 0111 and 12 if it is presented as 1100.
However, the digits 1100 and 0111 are called binary digits. Binary digits are numbers
expressed in base 2.
The short form of writing binary digit, we pick B from binary and it from digit. Then
we make bit. Bit is a short from writing binary digit.
Counting bits.
A single digit in binary value is called a bit. For example;
There are 4 bits in 0111
0
Bit 1
1
Bit 2
1
Bit 3
1
Bit 4
There are 8 bits in 10010001
1
Bit 1
0
Bit 2
0
Bit 3
1
Bit 4
0
Bit 5
0
Bit 6
0
Bit 7
1
Bit 8
Storing data in bits
A computer stores all forms of data or instructions in binary digits (bits). Personal
computers are designed to store these bits in groups of eight (8) binary digits (bits)
called bytes. A byte is set of 8 binary digits (bits). Long ago computer used to store
data in nibbles. A nibble is a set of 4 binary digits (bits).
4 bits ----------------------1 nibble
2 nibbles ----------------- 8 bits
Computer space is
measured in megabyte.
8 bits ----------------------1 byte
1024 bytes----------------1 kilobyte (kb)
1024 kilobytes ---------- 1 megabyte (mb) – SI unit used to measure computer storage.
1024 megabytes---------1 gigabyte (GB)
1024 gigabytes --------- 1 terabyte (TB).
Activity 1
24
1. The storage unit is made up of the ……………………….. and
the………………………….
2. The computer space is measured in…………………………………………..
3. When the storage space has run out of the computer‟s hard drive, one must try to
……………………. unnecessary files or use the …………………… memory.
4. A nibble consist of ………….bits while a ……………….has 2 nibbles.
5. …………………………………… is the static and non-volatile memory of the
computer system
6. List two primary memory of the computer system.
……………………-…………
………………………………
7. ………………… make 1 gigabyte.
8. Convert 8 into a binary digit.
25
System and Application Software
UNIT THREE
SOFTWARE
Software unit
Software is a set of instructions which a computer follows in
order to perform a given task. This means that it is a part of a
computer which you can see but you cannot touch it. For a
computer to work, you need to feed it with sets of instructions
which will command it to perform a given task. These
instructions are grouped and stored in files. The processor
unit names each file input into the computer with a unique
name for example, “love is beautiful.mp3”. This name “love is
An Empty Folder
beautiful.mp3”should be the only file with that name in a Fig 1.
particular computer folder. The process of naming computer files is called registry. Files
are stored in folders (shown in fig. 1). A folder is a means of storing computer files.
Folders of computer instructions are therefore, stored in a computer storage unit called
Read Only Memory (ROM).
Types of multimedia files.
o
o
o
o
Text files
Graphical files
Video files
Audio files.
This means all software files are stored in the computer hard disk (ROM)
Binary and software
It is very hard, nearly impossible to create sets of instructions (software) using binary
codes (1s and 0s). This is because it consumes a lot time and effort to just make a
complete single instruction. For this reason, humans prepare instructions in a language
almost the same as ours using English characters such as words, symbols, and signs
called high-level computer language. The process of writing computer instructions
using a computer sensible language is called programming. A person who writes
computer instructions is called a programmer. A high-level computer language is easier
to be understood by the human mind. All instructions are written and stored in a
computer language. However, a computer will later compile (using a compiler) the highlevel computer language and translate it (using a translator) into binary digits.
Computer languages
26
1. High-level computer language
o Hypertext markup language (HTML)
o Cascading style Sheet (CSS)
o Python
o Structured Query Language (SQL)
o Hypertext Preprocessor (PHP)
o C# (C-sharp)
o C++
2. Low – level Computer Language
o COBOL
o UNIX
TYPES OF SOFTWARE
The types of software are determined by what each type of software does. There are mainly
three types of software.
1. System software
System software is software which allows other software to function on a computer
system. It is made up two main parts;
 Operating system
This is the part of the system software that manages application software in
the computer system. it allows the following things to happen on a
computer system;
 It starts the computer when turned on. And it switches the
computer off.
 Application software to run
All application software run on top of the operating system.
 Protection of the computer hardware.
All computer hardware are allowed and managed by the operating
system.
 Utilities
This part of the system software manages the computer usage on daily
basis. Utilities make sure that the computer is protected from external
threats such as viruses, therefore, it contains that antivirus to protect the
computer. other functions of the utilities are;
 Manage files
 Manage peripheral drivers
 Manage task and tools bar.
27
The following are examples of system software.
i)
Microsoft windows OS
ii)
Linux OS
iii)
Macintosh OS
iv)
Android OS
v)
iPhone OS
Android OS and iPhone OS are system
software used to run on mobile phone
systems. Some other mobile phone systems
like NOKIA is run by Windows OS. This
means that Microsoft windows OS was
trimmed down to work on mobile phone
system. Therefore, the Microsoft Windows
operating system used in Mobile phones is a
trimmed-down system software. Trimmeddown software is desktop personal computer
software which is also used in a mobile
phone device.
OS stands for Operating
System.
Fig. 1 Microsoft Windows OS
Display
Functions of system software
i)
ii)
iii)
System software allows other programs or software
to work on a computer system. This means that, the
A computer user is
system software is responsible to give permission to
any person using a
other software to operate on a computer system.
computer system.
System software provides user–interface. The userinterface is the point of interaction between a
computer system and the user. The system software makes the computer
system easily operated by computer users. Some system software use pictures
(graphics) to represent computer programs and processes.
The system software is used to assign specific hardware devices connected to
the computer to input, store or output intended data or information. For
example in order to output sound (audio) information, a speaker will be
assigned by the operating system.
2. Application software
Application software is a type of softwares used to perform a specific task. There are
hundred-thousands of different tasks under the sun today. However, there are often
28
two or more application softwares created to perform just one task. This means that,
there are as many application softwares as the number of different tasks in the world
today. Every day, people are discovering new tasks and programmers are creating
new application softwares for each task. Sometimes application softwares are
referred to as web application or app.
The following are examples of application softwares.
1. Productivity application software.
Sometimes called productivity tools, application softwares package are used to
accomplish tasks related to manipulating and manage texts, numbers, pictures,
audio and videos. Productivity tools are commonly used in offices. Examples of
productivity tools are;
 Word processor (such as Microsoft word)
 Spreadsheet (Microsoft excel, and apple numbers)
 Desktop publisher (publisher)
 PowerPoint (PowerPoint presentation)
2. Browsing application software package.
Browsing application software package are software that allow users to send and
receive information and search for information on the internet. The following are
examples of browsing application software package.
 Google chrome
 Mozilla Firefox
 Microsoft Edge
 Internet explorer.
3. Audio player application software.
 Windows media player
 VLC
 Spotify
 iTune
4. education application softwares
 Joomla
 Teachable
 Moodle
3. Malicious software
Malicious software is software which is created to destroy or harm the files store in
the computer system. Malicious software damages, or mostly changes the
29
instructions of the computer programs. This makes the programs to malfunction or
fail to work. The following are the examples of the malicious softwares.
o Virus
o Trojan
Ways in which viruses can spread
Viruses mostly damage the computer files that other malicious software. A computer
can easily be affected by viruses if;



A computer user shares resources with other computers or storage devices
such as flash drives which may contain viruses.
A computer user downloads files such as computer programs, music, videos,
pictures and documents from unknown sites. Some sites have a tendency of
embedding viruses to musical, video, graphical and text files so that internet
users can download them.
A computer user connects storage devices such as flash drive, Compact disks
and external hard drives which are infested with viruses.
There are so many
Computer instructions are written in a computer sensible language. A computer sensible
language is a pattern of symbols, signs, letters and numbers used
30
Microsoft Word, Microsoft excel, and Microsoft PowerPoint
UNIT FOUR
PRODUCTIVITY TOOLS
PRODUCTIVITY TOOLS
WORD PROCESSOR
A word processor is computer application software which allows a computer user to type,
manipulate and print text. Microsoft word is a good example of a word processor which we will use
as a point of explanation in this book. Microsoft word is a word processor which runs on Microsoft
windows operating system.
How to find and open Microsoft word program on windows.
STEP 1
STEP 2
In order to find Microsoft word on windows, you need to navigate the cursor to the bottom
left corner of the computer screen and click
the „Start’ button. There is a key on the
bottom-left corner of the Microsoft keyboard
with the Start Icon. You can also
press it as a start button.
This display below will appear. It suggests to you a list of installed application software you
may wish to choose from. All application software is arranged in alphabetical. The list of
application software on the left side is often long if there a lot of installed application
software.
Use a mouse to Scroll through the list of application software shown on the left side and try
to locate the word processor software named “word”. If you cannot find it, then move your
cursor using a mouse to the search engine (Type here to search) and click. Then use a keyboard
and type „word‟. Then the Microsoft word application software will appear in the list with
the icon shown below.
Click the word icon to open. Then click on blank document to start typing on a new page.
STEP 3
31
Microsoft word blank page
A word blank page is a white plain space where information is typed and manipulated. It
has three segments or parts namely; a header, a document and a footer. Each segment is
said to be active when it allows a user to insert text onto it. In order to make one segment
active, the user needs to use a mouse to navigate the cursor to that intended segment and
double click the right button of the mouse. Note that, when the header and footer are
activated, the document segment is deactivated or closed. The header and footer become
active at the same time. By default, word blank page opens with active document segment.
Header
A header is the top part of the word page. It is used for two key functions;
1. It is used to insert the page or document title. Whenever one is writing a passage, it
is very important to begin by writing the title of the passage. For example „JELITA
AND MULENGA‟ however, „JELITA AND MULENGA‟ is a title and is typed in the
header. A header should be typed in capital letters.
2. It is used to insert the page numbers. Page numbers which are inserted on the top
part of the page are inserted in the header.
Document
32
This is the part of the word page where texts, numbers and pictures are inserted and
manipulated. By default a word page open with an active document.
Footer
Footer is a bottom segment of a word page where page numbers and texts are inserted.
Footer is conversional used for inserting page numbers.
Quick access
A quick access is tool which allows a user to find most used operations on a more visible place. A
computer user can customize the quick access toolbar by adding or removing some operations.
Close button
Minimize button
Maximize Button
Tabs
Word
File
Home Insert
Design
Layout References
Mailings
Hello world!
Functions of the quick access buttons on the word document.
33
Review
View
Help
a) Save button
is clicked to command the computer to store the information you have
typed or inserted on the word document. When a user clicks the save button, the information
typed or inserted on the word document will be saved.
How to save the word document.
It is very important to save your document before you start typing any text. To save your
document, you need to select the exact folder where your document will be stored. Off
course you need to save in the computer. So you will choose
b) Undo button
is right clicked to return to the previous activities within the same word
page. The undo button takes the user a step back to the previous use
c) Redo button
is right clicked to ret
This application software is mostly used for office work. It helps people to type, prepare and print
text. Using a word processor, text is typed on blank page.
The importance of the word processor.
- It allows computer users to type words on a computer.
- It allows computer users to format the texts and print text.
- It enables computer user to prepare word documents like letters with little errors.
- It allows users to insert pictures in the document and edit them.
- It allows users to create charts.
This application allows you to type texts using a keyboard, change the size, style, and color of the
text.
FORMATTING TEXT
Text is formatted from the home tab. The home tab contains the following sections used to
format text.
-
Font section
Paragraph section
Font section
To format text is to change the way text appears or looks. There are so many ways in which
text is formatted. Below, we will discuss ways in which text can be formatted. In this topic
will use the word „font‟ more that the word „text‟.
34
12
2. Size of the text – font size. (keyboard shortcut to changing the font size is ctrl+shift+P)
Text can be made big or small depending on the way the computer user wants. Just
like shoe sizes, text sizes are expressed in numbers called point (pt). so the bigger the
number the bigger the font size.
Below is a simple example of two different font sizes.
Font
18pt
Font
9pt
The recommended font size for official use is 12pt.
Grow font is used to make the font big while the shrink font is used to make the text
small.
1. Type of the text – font type. (keyboard shortcut to changing the font type is ctrl+shift+F)
Text can be written in so many different styles depending on the needs of the
computer user. Just the way we have different handwritings, texts can be differently
typed. Each font type is named with a unique name. Font type is sometimes called
font style.
Below is a simple example of how one word can be typed in different styles.
Font
Cambria (heading)
6.
7.
8.
9.
FONT
Algerian
Font
Times New Roman
Font
Arial Narrow
Font
script MT bold
Font
lucida console
Font
palace script MT
Boldface – boldfacing is the way of shading a text darker. The shortcut keyboard keys
for bold-facing are ctrl + B.
Font
not bold-faced
Font
bold-faced.
Italicize – to italicize is to slant the text forward. Shortcut keyboard keys for
italicizing are ctrl + I
Font
not italicized
Font
italicized
Underline – to underline text is to draw a line under the text. The keyboard shortcut
to underlining text is ctrl + U.
Font
not underlined
Font
underlined.
Subscript - creates the small letters below the text. e.g. x2 . You can use the keyboard
shortcut by pressing ctrl and =.
35
10. Superscript - creates the small letters above the text. e.g x2 . You can use the keyboard
shortcut by pressing ctrl, shift and =.
11. Font color – text can be painted in so many different colors of your choice. Users can
choose any color of their choice to color their texts. The default text color is black.
Black is also official font color.
5. Change case - this navigation allows you to make letter in a text to have CAPITAL
LETTERS, small letters, or mixED.
i.
Sentence case – this option allows you to set every first letter of a sentence
to capital letters.
ii.
lower case – this is also called small letters. this allows you to set texts to
small letters.
iii.
Capitalise Each Letter – This Allows You To Set The First Letter Of Each
Word To Capital Letter.
iv.
tOGGLE CASE – this ALLOWS you TO mix CAPITAL and small letters in
each word or sentence.
12. Text highlight color – this highlights the text. The text looks this way. Highlighted
3. Grow font – increases the font size.
4. Shrink font - decreases the font size.
Please not that: if you are manipulating typed text, then you must be first highlight
the text. To highlight the text is to drag through the text.
EXERCISE
1. What is the main function of the font section?
………………………………………………………………………………………….
2. Fill in blanks of the table below.
Name
Function
Symbol
Shrink text
Subscript
Font color
Font size
font type
3. To highlight is to………………………………………………………………………
36
PARAGRAPH SECTION
This section is responsible of arranging the text in a required order. in this section,
the text is nicely displayed on a page.
See the diagram below.
1. Bullets – this navigation allows you to add bullets to each paragraph in a passage. Often used
when listing items.
The example of bullets styles is shown below.
 Samuel
 James
 Harrison
 Lingson
2. Numbering – this numbers items using numbers, capital and small letters and roman numerals.
a. Samuel
b. Gift
1. James
2. Lingson.
3. Decrease indent – this indent pushed the texts towards the left part of the page.
Increase indent – this indent pushes the texts towards the right part of the page.
5. Line and paragraphing spacing: this navigation allows you to change the spaces between lines
and texts. It also changes the spaces made before and after a paragraph.
1.0 Spacing
1.5.Spacing
Line and paragraphing
spacing: this navigation allows
you to change the spaces
between lines and texts.
Line and paragraphing spacing: this
It also changes the spaces
made before and after a
paragraph.
navigation allows you to change the
spaces between lines and texts.
It also changes the spaces made
before and after a paragraph.
37
4. Left alignment – all highlighted sentences or text start from the left to the right part of the
page.
Centre alignment – all highlighted sentences or texts start from the middle of the page.
Right alignment – all highlighted sentences or texts start on the right side of the page.
Justify alignment – all highlighted text and sentences are set balanced. Justify allows you to
organize the work quite neat.
6. Shading – colors the background of the selected text or paragraph.
This is the example of shading.
7. Border shading – shades the border of selected text or paragraph.
The heading of the short article shown above is bordered.
This navigation allows you to border one side of at a time.
Bottom border – makes a line under selected text or paragraph.
Right border – adds a border line on the right side of selected text or paragraph.
Left border. – adds a border line on the left side of selected text or paragraph.
Top border – adds a borderline on top of selected text or paragraph.
No border –it removes all added borders to all selected text.
All border - it adds borderlines to all sides of the selected text or paragraph.
38
INSERT TAB
This tab allows the computer user to insert shapes, page numbers, tables, graphs and symbols.
Below is a list of functions of the insert tab. There are so many more to this tab.
A
B
C
D
E
F
G
H
I
A. Table: this navigation allows you to insert a new table on the word program. The user can also
draw a table.
Drawing the table, allows you to highlight boxes you would like to include in your table. It gives
you enough options on how many rows and columns you would like to use in your table.
B. Pictures and ClipArt – this area allows you to insert pictures and clip arts from your computer on
to a word page.
C. Shapes – this area helps the user to insert shapes of choice. It provides ways of resizing and
grouping them. To resize a picture is to change its size. To group is to bond two or more shapes or
pictures together.
D. Smart art – this is a graphic art inserted on to the word page to communicate information. Smart
arts explain ranges, processes, or lists.
E. Charts – just like any other chart, charts are used to relate or compare information. they are so
many charts to explore such as bar chart, pie chart, line chart and surface.
F. Screenshot – you can insert a picture of the current program that is open on your computer screen.
G. Links – this area allows you to connect the information you are typing to other books or content
either ;a. In your computer
b. On the internet using the Universal Resource Locator (URL)
c. On the other page of your document.
H. Header and footer – this area allows you to insert the header and footer. It is also allows you to
insert page numbers either in the header or in the footer.
I. Equations and Symbols – this navigation provides basic built in mathematics equations and
symbols. This area also gives you the ability to insert your own formula. You can create better
mathematical fractions using this area.
39
EXERCISE
1. Study the passage carefully.
CASE STUDY
Cleaners working for an employer in the northwest were using a whole range of cleaning products
from different manufacturers. The products were not labeled, so the cleaners did not know when and
where they should and should not use each one, or what safety precautions they needed to take. Using
unlabelled chemicals is extremely dangerous. Some must be diluted to a particular strength for safe
use. Others must never be mixed, such as acids (some cleaning agents) and bleach (an alkaline) for
risk of a dangerous reaction. Some cleaners had noticed that certain substances they were using
irritated their skin, others smelt strange and caused headaches.
The UNISON safety rep held a meeting with the cleaners to get their views and then carried out her
own inspection. She reported all the risks that she found, in writing, to management. She also asked
them for their COSHH risk assessments and for a meeting to discuss the problem. It transpired that
no formal COSHH assessments had been carried out. It was then agreed that management would
obtain all the manufacturers’ safety data sheets for each substance used, as a first step towards
conducting the assessments.
The UNISON branch reached agreement with the employer that only three main cleaning substances
would be used. These would be kept in different coloured and labeled containers and the cleaners
were to be given training in their safe use.
Answer the following questions
1. Name the type of alignment used in the passage above.
………………………………………………..
2. List three words that are italicized in the passage above.
………………………..
………………………...
3. Write the keyboard shortcut that made UNISON and COSHH bold.
…………………………………..
4. The word agreement in the last paragraph of the passage is …………………………..
2.
The graphical materials below were inserted in the word page.
i.
ii.
iii.
To group is to…………………………………………………
To resize is to …………………………………………………
To regroup is to ………………………………………………
3. Describe how you would make save a word document.
………………………………………………………………………………………………………
………………………………………………………………………………………………………
………………………………………………………………………………………………………
….
40
SPREADSHEET
Objectives




Define spreadsheet.
How to open the spreadsheet program
Understand how into insert formulas and functions
Use spreadsheet information to create graphs.
A spreadsheet program has a collection of utilities and operations that allow manipulation
of numeric (numbers) and text (letters and symbols). a worksheet is spread made of rows
and columns where information is entered and manipulated. The spreadsheet is a program
that allows creating reports that contains calculations and charts.
Worksheet
A worksheet is made up of rows and columns. The point where rows and columns meet,
cells are made up.
Rows and columns
Rows are space lines that run from left to the right of the spreadsheet. Rows are labeled by
numbers. These number labels of rows are already tagged by the spreadsheet program. This
means that, you cannot change or delete the number labels of the rows in the spreadsheet.
The diagram below shows the rows of the worksheet.
1
2
3
4
The diagram above shows 4 worksheet rows. A spreadsheet program has almost an endless
list of rows.
Columns are spacelines that run from the top part of the spreadsheet to the bottom.
Columns are labelled by block letters, that lies on the top part of the worksheet. These block
letters are automatically labelled by the spreadsheet program. This means that you cannot
change or delete the block lettered labels of the spreadsheet. The diagram below shows the
columns of the worksheet.
41
A
B
C
D
E
F
G
H
There are 8 columns in the diagram shown above.
Cell
A cell is a point where data is entered and manipulated. This means that, a cell is a point at
which a single column meets a single row. Cells are used to enter data or information. See
diagram 3, showing a single cell formed from row 5 and column H.
H
5
Cell
Diagram 3
Naming cells
Each column and row has a label. However, each cell in the spreadsheet is identified by a
unique name or label. The name of a given cell is joined from the row and a column that
makes it. If row number 5 meets with column H, a cell formed will be H5. See diagram 4
below.
H
5
H5
Diagram 4
Exercise 1
1. What is a spreadsheet cell?
………………………………………………………………………………………..
……………………
42
2. Study the spreadsheet diagram and answer the questions that follow.
a. Write the labels for the columns and rows of the spreadsheet shown above.
b. How many columns are shown above?.........................
c. How many rows are shown above?...............................
d. How many cells are in the worksheet shown above?.............................
e. Explain how to a cell in a spreadsheet.
………………………………………………………………………………………………
………………………………………………………………………………………………
………………………………………………………………………………………………
……………………………..
f. Name the shaded cell in the spreadsheet shown above.
………………………………
3. What is a spreadsheet?........................................................................................................
………………………………………………………………
43
.
Adjusting the size of a cell
The height and the width of a given cell can be adjusted by;
i.
i.
Widening or narrowing the column that makes it.
Heightening or shortening the row that makes it.
(Resize) Widening or narrowing the size of a column
If the column that makes a cell is widened, all cells in that column will increase their
widths. If the column that makes a cell is narrowed, all cells in that column will reduce
their widths.
Practical : In order to widen or narrow the column, move your cursor on the right side
boundary line of a column you wish to widen, where your cursor style
turns this,
then, right click and drag. While dragging, you can drag the cursor rightward to widen or
drag the cursor leftward to narrow the width of the column and its cells. See diagram 5
below.
Cursor used to widen or
H
5
narrow a column and its
cells
Cell
(Resize) Heightening or shortening the size of a row.
If the height of a given row is increased, all cells in that row will increase in size as well.
When the height of a given row is reduced, all cells in that row will reduce in size as well.
Practical : In order to heighten or shorten the size of a given row and its cells, move
your cursor on a bottom boundary line of a row, where your cursor
44
style turns this,
then, right click and drag. Then you can drag and move the cursor up to reduce the height
of row and its cells, or move down to heighten the size of a row and its cells. See diagram 5
on the next page.
H
5
Cell
Practical: Click on a cell of your choice to enter information. Double click to edit
information in a cell.
Spreadsheet cursors
With the spreadsheet work we have covered so far, the following are the spreadsheet
cursors you are like to find as you use the spreadsheet.
Name
Cursor
Use
Navigating cells on a
worksheet. Pointing cells.
Point and highlight the
whole column.
Point and highlight the
whole row.
Adjust the height of the
rows and their cells.
Adjust the width of the
columns and their cells.
Navigating and selecting
spreadsheet ribbon.
Merging cells and center information
To merge cells is to join two or more cells into a single cell. Mostly cells are merged in order
to create enough space for entering information. Merged cells are treated as a single cell.
45
Practical : in order to merge cells, highlight the cells you wish to merge. Click on
in the Home Tab Ribbon. In a spreadsheet, to highlight is to click and drag
through the cells or text.
Naming the merged cell
The merged cell inherits or gets the name of the cell that the user started by highlighting. If
a user starts by highlighting cell C2 through to cell F2, then the name of the merged cell will
be C2. See fig 6 below.
A
B
C
D
1
2
3
4
5
6
7
E
F
G
C2
Exercise
1. Study the spreadsheet below.
A
B
1
2
3
4
5
6
a. Name the cells that have been merged in the spreadsheet above.
………………………………..
………………………………..
………………………………...
………………………………...
………………………………...
b. How many cells are shown in the spreadsheet above?
……………………………………
c. Explain how you would widen column B.
……………………….
46
H
I
Fill Handle
The Fill Handle is in the bottom right corner of the selected cell. When you place your
mouse over this handle, it changes from a thick white cross, to a thin black cross (+). Once
you see the thin cross (no arrows) you can click and drag the cell to fill its contents in a
single direction (up, down, left or right). If you want to go in two directions, you must first
complete one way, let go of the mouse and then drag the handle in the second direction.
When you use the Fill Handle to pull down a single number or plain text, it will copy the
data. When you use the Fill Handle to pull down a text with numbers, a date, a month or a
weekday it will fill in a series.
When you select two or more numbers (including dates) and then use the Fill Handle, Excel
will fill in the series, following the original pattern of the selected cells. It can only follow
simple addition and subtraction patterns.
In this topic, we will use the fill handle to replicate information, numbers and formulas.
47
Formula and functions
The biggest power of excel is its functions that you can you can use to perform a lot of
calculations.
Spreadsheet program has a number of built-in formulas called functions, which makes a
spreadsheet program to be used for calculations. Spreadsheet functions will operate the
following operations.
Insert a formula or a function in a spreadsheet cell.
Always a spreadsheet formula begins with an (=) sign.
i.
Sum function: this function adds all highlighted range of cells in the worksheet.
With this function, you can add the total value of many cells. In the example
below, we will add the total scores of sections A, B and C for Nyambe Dorothy in
cell E3.
However, we will insert the following function;
=SUM(B3:D3) then press ENTER key.
A
B
FULL NAME
Nyambe Dorothy
John Hallows
Evelyn Sankata
Dalitso Shane
ii.
D
E
Section A Section B
15
43
23
34
22
23
32
34
Section C
30
27
43
23
TOTAL
88
=SUM(B3:D3)
Average function: this function finds the average of a highlighted range of cells.
This function calculates the average of numeric values. The using the diagram
below, we will calculate the average of results of Section A. The function
=Average(B3:B6) is inserted in cell B7
A
1
2
3
4
5
6
7
C
GRADE 9B COMPUTER STUDIES RESULTS
1
2
3
4
5
6
7
B
C
D
GRADE 9B COMPUTER STUDIES RESULTS
FULL NAME
Nyambe Dorothy
John Hallows
Evelyn Sankata
Dalitso Shane
AVERAGE
Section A Section B
15
43
23
34
22
23
32
34
23
=Average(B3:B6)
48
Section C
30
27
43
23
E
iii.
Count function: this function finds the number of values in a highlighted range of
cells. In simple terms, this function counts the number of cells that you have
inserted numbers into. It does not count cells that you have inserted letters or
letters with numbers but counts only those cells with number values only.
Look at the diagram below. The function =count(A4:D4) is inserted in cell E4.
A
1
2
3
4
5
6
7
B
C
D
E
GRADE 9B COMPUTER STUDIES RESULTS
FULL NAME
Nyambe Dorothy
John Hallows
Evelyn Sankata
Dalitso Shane
Section A Section B
15
43
23
34
22
23
32
34
Section C
30
27
43
23
3
=Count(A4:D4
)
The count function in the diagram above has only counted cells with number values only.
iv.
Max function: find the largest value in a highlighted range of cells. This function
returns the largest numeric value. The MAX function is inserted in cell E5 to find
the largest score for Evelyn Sankata‟s Sections. = MAX(B5:D5). Below is the
diagram diagram showing the.
A
v.
vi.
B
C
E
GRADE 9B COMPUTER STUDIES RESULTS
1
2
FULL NAME
Section A Section B Section C
3
Nyambe Dorothy
15
43
30
4
John Hallows
23
34
27
5
Evelyn Sankata
22
23
43
43
6
Dalitso Shane
32
34
23
=MAX(B5:D5)
7
Min function: finds the smallest value in a highlighted range of cells. The Min
function is the exact opposite of Max function.
Now function: this function returns the current date and time of your computer
system at the time you have entered the function.
=Now() is inserted in cell A1. The result shown in cell A1 indicates the date and
time at which this function was entered in cell A1.
A
1
2
D
B
19-05-22 22:40
49
REPLICATION: this is the copying of a value through other cells. Replication is commonly
done to copy formulas. Sometime it is very time wasting to type a formula to add all
sections for each pupil. In order to do that easily, one function can be replicated through
other cells. Look at the table shown below.
To replicate a
A
B
C
D
E
GRADE 9B COMPUTER STUDIES RESULTS
1
2
3
4
5
6
7
FULL NAME
Nyambe Dorothy
John Hallows
Evelyn Sankata
Dalitso Shane
Section A Section B
15
43
23
34
22
23
32
34
Section C
30
27
43
23
TOTAL
=sum(B3:D3)
function, move
your cursor on
bottom right corner
of the cell until the
cursor turns into a
sign, and then
drag through other
cells.
Exercise
1. Study the spreadsheet below showing Munachika shopping centre stock records.
1
2
3
4
5
6
7
8
9
10
A
Product
Sugar
Salt
Washing Powder
Mealie Meal
B
Description
2Kg
1Kg
500g
25Kg
C
Quantity
8
2
5
1
D
Unit Price
K42.00
K5.00
K15.00
K198.00
Total
a. Fill the following details in the table above.
o 4 packets of lollipops bought at K23.50N.
o 18 boxes of tomatoes ordered at K150.00
o 6 pairs of shoes bought at K750.00.
o 140 rims of paper bought at K107.00.
b. Write the formula in cell E2 to calculate the price of sugar.
………………………………
c. find the result of the formula inserted in cell E2.
……………………….
d. The formula in cell E2 was copied through to cell E9, which is
called…………………….
50
E
Price
e. Insert the function on cell E10 that calculates the total.
………………………
f. Write down the result of the function inserted in cell E10.
Spreadsheet Charts
What makes spreadsheet program so special is its ability to translate information and
numbers into charts. A chart is a graphical representation of information. A spreadsheet
program supports various types of charts. Some common charts are listed below.
o
o
o
o
o
Pie chart
Column charts
Bar charts
Line charts
Scatter chart.
Creating a charts
We will use a simple spreadsheet information to create Charts.
Munachika Shopping centre stock record
2
3
Matches
Giggies
100 sticks box
5kg bag
343
20
D
Unit
Price
2
23
4
Coca-Cola
500ml
200
7
1,400.00
5
Fanta
750ml
360
7
2,520.00
1
A
B
C
Product
Description
Quantity
E
Price
686.00
460.00
Step 1:
In order to create a pie chart of the prices of products, you need to highlight the cells
holding values of prices and the cells holding the names of the products.
51
After highlighting the price column, then highlight the column with names of products. Do
all these while pressing control (ctrl) key on the keyboard. At the end, all columns must be
highlighted. Note: do not click anywhere in the worksheet after highlighting.
Step 2
Navigate your cursor on the ribbon‟s insert tab and click.
Click on pie.
This process is done for any type of chart you would like to make. You may pick column
chart, bar chart, area or line chart. The process is the same.
Step 3
When you click on pie, a drop of options will appear.
We will click this 2-D style of a
pie chart to make a pie chart.
Step 4
A pie chart of the information in the spreadsheet is created.
52
Step 5
You can decide how you would want information to appear in the pie chart using the chart
layout.
Using the chart layouts, you can select one of the chart layouts. Below are some of the chart
layout and their results based on the same information.
53
Show Formula
Spreadsheet formulas are always hidden behind the results. Most often after preparing a
good stock record, one would want to see all the formula used in the spreadsheet.
Here is how spreadsheet formulas are shown.
Step 1
Highlight the worksheet area you are intending to see the formulas.
54
Step 2
Navigate your cursor on to the spreadsheet ribbon and click the formulas tab.
Step 3
On the formulas bar, find and click „show formulas‟.
All formulas in a highlighted area of a spreadsheet will be displayed or shown.
55
Printing a work sheet
Printing is producing a computer graphical or textual file on a paper using ink. During this
process, a printer is used as an output device to produce a hardcopy of the softcopy file. In
spreadsheet, here are step by step instructions to printing a worksheet.
First you need to bear in mind that, spreadsheet will allow you to print the following
printing areas;
-
The entire workbook
The active worksheet
Print selection.
Step 1
Navigate your cursor to the spreadsheet ribbon and click „file’ tab
File tab drops down a list of options. You need to navigate to
„print‟.
Click ‘print”
56
Step 2
Click the „Print‟ option. It is easy to print the worksheet by following these simple
instructions.
Command to
print
5
Type the number of
copies to be printed 2
Choose the
printer to use.
1
Page preview
Choose the range of
pages to be printed. 4
3
Choose the area to
print.
-Entire workbook
-Active sheet
-Only selected
It is very important to highlight or select a range of cells
Highlight the area you wish to print.
57
POWERPOINT
PowerPoint is a program that uses text, pictures, videos and audio in order to communicate
ideas. PowerPoint supports all multimedia. These are;
-
-
-
Audio – you can add and manipulate sounds such as song.
Audio is manipulated by;
o Trimming – removing unnecessary parts of an audio file.
o Volume – determining how loud or low the sound is.
o Pace – the rate which the audio file is played.
Text – you can type and manipulate letter, numbers and symbols.
Text is manipulated by;
o Formatting text color, style, size, spacing and alignment.
Video – you can add and edit videos using the PowerPoint.
Video is manipulated by:
-
o Trimming – removing unnecessary parts the video.
Pictures – you can add and edit pictures.
POWERPOINT RIBBON
1. HOME TAB
1
1
2
3
Font - this area of the home tab manipulates letters in a document.
This area is responsible of manipulating the text (letters, symbols and numbers) in the
following ways:
NOTE: in order to manipulate given texts, you must highlight it.
58
a. Font type:
People have different handwritings. Also a computer provides different ways of
writing text. Below is a single text typed in three different font types.
Heading (agency FB)
Heading (Times New Roman) - this font style is recommended for academic writing.
Heading (Bradley Hand ITC)
The word processor program provides a variety of font styles to choose from.
b. Font size: this adjusts the size of the text. The sizes of texts can be typed in the
space provided or a user can choose from the range of sizes provided by the
program. The recommended text size 12pt for formal documents. 16pt can be
used when typing heading. The texts below are typed in different font sizes.
Heading 10pt
Heading 12pt
Heading
16pt
Heading 28pt
c. Grow and shrink font can be used to make the font size bigger or smaller.
Shrink font
Grow font
-
By clicking at the Grow font, the highlighted text becomes bigger.
By clicking at the shrink font, the highlighted text becomes smaller.
d. Change case
Change Case
this navigation allows you to make letter in a text to have CAPITAL LETTERS,
small letters, or mixED.
v.
Sentence case – this option allows you to set every first letter of a sentence
to capital letters.
vi.
lower case – this is also called small letters. this allows you to set texts to
small letters.
vii.
Capitalise Each Letter – This Allows You To Set The First Letter Of Each
Word To Capital Letter.
59
viii.
tOGGLE CASE – this ALLOWS you TO mix CAPITAL and small letters in
each word or sentence.
e. others
1. Bold-facing – shades the highlighted texts. This means that, the bold-facing
navigation makes the color of the text darker. You can use the keyboard keys
to make text bold by pressing. CTRL + B.
2. Italicising – this navigation makes texts thin and slant forward. You can use the
keyboard keys to make text italicised by pressing. CTRL + I.
3. Underline – this navigation underlines the text you have highlighted. You can
use the keyboard keys to make text underline by pressing. CTRL + U.
4. Text shadow – this navigation slightly works like bold-facing. It adds the
shadow to the text.
5. Strikethrough – this draws a line though the middle of a selected text.
6. Character spacing – this adjusts the space between letters in a word.
Very tight –
Tight Normal – the distance between letters is normal.
Loos - l e t t e r s a r e f a r t o e a c h o t h e r.
Very loose - l e t t e r s a r e v e r y f a r a p a r t t o e
a c h o t h e r.
7. Font color – this navigation allows you to choose the color of your text. Black
is the default font color.
8. Font formatting – this navigation erases all the manipulations you made on
the fonts and return all to default.
o
o
o
o
o
2
Paragraphing – this area of the home tab arranges texts in different manner. some of which
are;
-
Bulleting
Text alighments
Line spacing
60
The picture below will be used as a point of reference.
1
6
2
7
3
8
9
4
5
10
3. Bullets – this navigation allows you to add bullets to each paragraph in a passage.
Often used when listing items.
The example of bullets styles is shown below.
 Samuel
 James
 Harrison
 Lingson
4. Numbering – this numbers items using numbers, capital and small letters and roman
numerals.
a. Samuel
b. Gift
4. James
5. Lingson.
6. Decrease indent – this indent pushed the texts towards the left part of the page.
7. Increase indent – this indent pushes the texts towards the right part of the page.
8. Line and paragraphing spacing: this navigation allows you to change the spaces
between lines and texts. It also changes the spaces made before and after a
paragraph.
2.0 Spacing
1.6.Spacing
Line and paragraphing
spacing: this navigation allows
you to change the spaces
between lines and texts.
Line and paragraphing spacing: this
It also changes the spaces
made before and after a
paragraph.
navigation allows you to change the
spaces between lines and texts.
It also changes the spaces made
before and after a paragraph.
9. Left alignment – all highlighted sentences or text start from the left to the right part
of the page.
61
10. Centre alignment – all highlighted sentences or texts start from the middle of the
page.
11. Right alignment – all highlighted sentences or texts start on the right side of the
page.
12. Justify alignment – all highlighted text and sentences are set balanced. Justify allows
you to organize the work quite neat.
13. Columns – this splits the text into two or more columns.
Others
Text direction: this navigation allows you to change the orientation of the texts. Using this
option, you can rotate text to a certain degree.
Align text is the way text is aligned within a text box. You have covered this on right, left,
and centre and justify alignment.
SmartArt: this allows you to change texts to smart graphical diagrams.
62
For example the process of going to school
Wake up
Brush your teeth
Take a shower
Eat your break fast
Put on a uniform
3
Drawing – the drawing navigation mainly contains the shapes and
2
1
This part of the PowerPoint allows you to insert and resize shapes.
1. A computer user can insert various shapes when creating diagrams.
Some of the shapes you would need to try are listed below.
63
Manipulating shapes
Whenever a shape has been inserted in the slide, an extra tab called format is added
on the ribbon. The format tab is used to manipulate the shape or
shapes
added.
1. Resizing – This is the ways in which the size of the shape can be
The size of the shape is adjusted from the resize handles.
changed.
Resize handles
2. Grouping – when two or more shaped are added to the slide, the user can group
the shapes so that they appear as a single shape.
How to Group shapes.
Click on every shade you have added to the slide while holding the CTRL key of
the keyboard. Note: you only click on a shape when the cursor adds a plus sign
on top and a small dashed box below.
3. Shape fill and shape outline
Shape fill paints the inside of the selected shape. While the shape outline paints
the outside part of a selected shape.
Shape fill
Shape outline
64
2. Arrange
Arrange navigation contains the following;
- Order object
In short, order objects means arranging shapes and pictures in order.
i.
Order – this is the process of arranging shapes and pictures in a way
that can be manipulated. Order object allows computer users to bring
one shape in front of the others called bring to front or send one shape
or picture behind others called send to back. Sending one shape above
the other, is called bring forward while sending one shape below the
other is called send behind. Using order object a user can also send
shapes and picture behind or in from the text.
ii.
Grouping – grouping is the way of attaching two or more shapes
together. When two or more shaped are added to the slide, the user can
group the shapes so that they appear as a single shape.
How to Group shapes.
Click on every shade you have added to the slide while holding the
CTRL key of the keyboard. Note: you only click on a shape when the
cursor adds a plus sign on top and a small dashed box below.
Exercise
1. Draw the symbols or shapes representing the following terms in the table below.
Term
Symbol
Boldface
Italicize
Justify
INSERT TAB
In PowerPoint, insert tab allows the computer user to add objects and media files on
a slide.
Below are some of the objects and media files that can be added on a slide.
1. Objects
o Tables
o Shapes
o Charts and smartArts
65
o Header
o wordArt and
o symbols
2. Media files
o pictures, clipArts and screenshots.
o Videos
o Audio
Formatting media files
Media files can be formatted in ma
i.
Pictures, ClipArt and Screenshot.
pictures, clipArts and Screenshots can be formatted by;
-
ii.
Resizing
Order objects
Grouping
Cropping
Videos - a video file can be added to a slide from the computer file or website.
However it can be formatted by trimming. Trimming is the process of
removing unnecessary parts of the video file.
Audio – an audio file can be added or inserted on to a slide from the computer
file or direct recording. However, it can be manipulated by trimming.
iii.
Transition is the movement of slides from one to the other. Transition tab contains so
many transition styles. This tab contains navigations that manipulate the movement
of slides from one to the next.
Transitions can be set to happen on every mouse click or automatic.
-
Mouse click – mouse click allows user to see the next slide after a click.
After – Duration on a single slide is set before moving to the next slide. This
means a certain number of seconds or minutes must be reached before moving
to the next slide.
Timing
Each transition is timed. The movement of one slide to the next can be either be fast
or slow. For uniform transitions, each transition of a slide is timed per 1 sec. this
means that the change of one slide to the next takes a second.
66
Sound
You can also accompany each slide with a sound. To attract the attention of the
audience, every transition is introduced by a beep of sound. There are so many
sounds you can choose from.
ANIMATION TAB
Animation
This is the tab that allows each object inserted on a slide to appear. It contains many slide
animations such as fly-in, float – in and fade. Each animated object, text or picture will
appear in a slide in the way it has been animated.
Timing
Duration
Equally, each animated object will appear on a slide at a speed it has been set. If a text is set
to animate in 4s, it will appear with the duration of 4s.
Onclick
This navigation allows users to animate texts, pictures, videos, objects and audio files on a
slide per click.
Delay
Delay allows automated animation. The next object or file on a slide will animate after a
particular period of time. If delay is set as 8s. This means that a picture will be displayed for
8s after that, the next object will be displayed on the same slide.
67
LAN, WAN, MAN, SAN, AND INTERNET.
UNIT FIVE
NETWORK
Network
To network is to connect two or more computing devices in order to share computer files.
- When you connect your phones using Bluetooth, you have networked.
- If you connect your phone to a computer using a universal Serial Bus (USB)
cable, that is network.
- If you connect your computer to your printer in order to print something, this
means that you have networked.
Advantages of network


Sharing files such as music, photos and documents is easy and fast.
It is cheap to share files when computing devices are networked.
Disadvantages of network


Viruses easily spread on a network.
Connecting devices over a distance is expensive.
Forms of network
The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or
infrared light beams.
1. Wired – this is the way of connecting computer devices using a cables. Such as using
- USB cable.
- Ethernet cable.
2. Wireless – this is the way of connecting computer devices using signal. Such as using
- Radio wave (Bluetooth)
- Telephone line
- Infrared light beam (like in remote control)
- satellites (Signal used in Routers such as MiFi and WiFi )
EXERCISE
1. What is network? ……………………………………………………………………………..
………………………….
2. Give one ways in which you can create a network.
…………………………………………………………
3. Give one disadvantage of using network.
68
……………………………………………………………………..
4. Give one importance of using network to share resources.
……………………………………………………………………………………………..
69
TYPES OF NETWORK
There are two basic types of network. There are so many others, that we will discuss.
The types of network usually depend on distance that the computing devices are able
to connect.
Distance and network
 Bluetooth is 10 meters.
 USB cable is dependent on the length of the cable.
 Router 100 meters.
The following are the basic types of network.
1. Local area network (LAN)
Local area network is the connection of two or more computing devices within
the same geographical area. Commonly used within a workplace or home. This is
the most common used type of network when sharing resources. A Local Area
Network (LAN) is a network that is confined to a relatively small area. It is
generally limited to a geographic area such as a writing lab, school, or building.
- When you connect your computer to your printer in your home or office, you
have then created a LAN.
- In big companies, where there is only one printer used by different offices
within the same place, a LAN is created to connect all computers to print
using the same printer.
Advantages of LAN.
-
LAN is easy to set up
LAN is cheaper to setup
LAN does not need the expertise knowledge to connect.
Disadvantages of LAN
-
Viruses easily spread on LAN
When too many computing devices connected, the LAN becomes slow.
WLAN – Wireless LAN is when you connect two or more computing devices
using signal. Bluetooth is a good example of WLAN. Modulator – demodulator
(Modems) is also a good example of WLAN that is used to connect a large
number of computers at a workplace.
2. Wide Area Network (WAN)
This is the connection computing devices across different geographical area.
WAN is made up by joining two or more LANs. It is often wireless WAN
(WWAN) because;
70
-
It uses satellites (in Zambia we have Mwembeshi Satellite)
Microwaves.
A school has branches all over the country. Each branch has a local area network. The
school management decides to connect all the branches under one network. However, the
school computer teachers connect each branch to another until the branches are connected
together. After all branches are connected together, it is called Wide Area Network.
Other networks
3. Personal Area Network (PAN) – this is the personal organized network. For
example; if you connect one phone to the other using Bluetooth.
4. Storage Area Network (SAN) is the connection of two or more computers to a
server in order to provide storage backup. For example; if you connect your
computer or mobile phone to Google drive to be automatically storing your files.
5. Metropolitan Area Network (MAN) - this is the wide area network confined to a
city.
Network topology
Network topology is the layout of computing devices in a network. Computers are
connected to each other in a certain way. The following are the most common network
topologies. the word „station‟ will be used to refer to a computer in a network.
1. Bus topology is the kind of topology where each computer is connected to a single
cable. Sometimes called line topology.
Advantages of bus topology
o It works well when you have a small network.
o It's the easiest network topology for connecting computers or
peripherals in a linear fashion.
o It requires less cable length than a star topology.
Disadvantages of bus topology
o It can be difficult to identify the problems if the whole network goes
down.
o Bus topology is not great for large networks.
2. Star topology is one of the most common network setups. In this setup, every
computing device in the network connects to a central network device called a hub.
71
Examples of hubs are routers. The central network device acts as a server and the
peripheral devices act as clients.
Advantages of star topology
- It is easy to add another computer to the network.
- If one computer on the network fails, the rest of the network continues to
function normally.
Disadvantages of star topologies
-
Can have a higher cost to implement, especially when using a switch or
router as the central network device.
The central network device determines the performance and number of
nodes the network can handle.
If the central computer, hub, or switch fails, the entire network goes down
and all computers are disconnected from the network
3. Ring topology
This is the connection of computing devices in a circular manner. In this kind of
topology, data travels from one computer to the next until it reached the destination.
Some ring topologies allows you data to flow clockwise or anti-clockwise and other
ring topologies are designed to allow data flow in both direction.
Advantages of ring topology
- It is very easy to setup
- Data travels faster
Disadvantages of ring topology.
- If there are a lot of connected computers, network becomes slow.
4. Mesh topology
This is the connection each computer to all others.
Advantages of a mesh topology
-
Mesh topology is very fast and efficient
72
-
A failure of one device does not cause a break in the network or
transmission of data.
Adding additional devices does not disrupt data transmission between
other devices.
Disadvantages of a mesh topology
-
It is very expensive to setup a mesh topology compared to other
topologies..
Building and maintaining the topology is difficult and time consuming.
5. Hybrid topology
This is the joining of two or more topologies together. If you can connect star
topology to bus topology, then you make a hybrid topology. The diagram below
shows a star topology made up bus topologies.
EXERCISE
1. Give three type of network.
………………………………………………..
………………………………………………..
……………………………………………….
2. Define network topology…………………………………………………………………….
…………………………….
3. List four network topologies
……………………………………..
……………………………………
……………………………………
…………………………………..
4. Which topology is made up by joining two or more other topology?
……………………………………………..
5. Define the following terms.
i)
Hub
ii)
Node
iii)
Modem.
73
Internet
Today we have hundreds of thousands computers connected to each other on wide area
network using satellites. This allows to access information in servers computers located in
different parts of the world. This system of connected computers in the world is called
World Wide Web (WWW)
i. Universal Resource Locator (URL)
The heart of internet is the Universal Resource Locator (URL). A URL identifies the specific
location of the computer on the internet. E.g. www.thornhill.com. The phrase, .com is the
domain. The internet has been organized into major domain refered to at the end of the URL
such as .com-commercial, .edu – education, .gov – government, .mil-military, .orgorganization and .net – internet service providers, network companies and other groups
concerned about the internet.
ii. Internet Protocol Address (IP)
An internet protocol is the right step by step way of sending and receiving information
across networks.
Please get reminded that a computer understands everything in 1s and 0s. so computers
will always bring things down to numbers.
When you type www.thornhill.com and search, the computer interprets that into groups of
numbers called an internet protocol IP address that looks like this 123.45.23.331. This IP
address is like the house number. Each computer has a unique number that is used to be
identified on the internet. And that number is the IP address.
However, the URL and IP address are used to locate the exact computer you want to access.
iii. Email
Electronic mail is heavily used feature on the internet today. You can use it to send
messages to anyone who is connected to the internet. Millions of people send and receive
mails every day. Email is the best way to keep in touch with family, friends, relatives and
co-workers living very far from us.
Like most internet data, the Transmission Control Protocol (TCP) breaks the message in an
email into packets. then the IP delivers the packets to right location following the Universal
Resource Locator. When it arrives at the right computer, the TCP reassemble the packets
into readable messages on the receiving email server.
On the email, you can attach files such as files, videos, pictures and sound called
attachments.
iv.
Spam
74
We cannot discuss mails without talking about spams. Spam is email that is not requested to
be sent which contains advertisement materials. Spam emails are sent commercially
containing phone number, website address and gallery of products for sale.
Spams are one example of junk mails. They are sent in bulk, therefore congest the internet
pipeline which causes internet to be slow. Spams also cause email lost. You can block
spams.
v.
Intranet
Intranet
Intranet is the secured connection of computers within an institution. Intranet is meant for
people working within that institution only to access the network. It secures the company
from intruders to have access to the company resource such as the company video
conferencing meeting, databases and group emails.
With the growth of businesses today, the need to provide private network within a company has risen.
Under intranet companies such as banks would want to share some private information like account
details with its clients, however, they would create an intranet.
When using intranet, internet connection in your company is separated from the rest of the
world using software called firewall. Which means no one can access your internet in your
institution.
EXERCISE
1. Define the following terms
i.
Spam
ii.
Junk mail
iii.
Intranet
iv.
internet
2. What do the following abbreviations stand for?
i.
URL
ii.
WWW
iii.
IP
iv.
TCP
3. What is an email?
………………………………………………………………
4. Explain how the message is sent using email.
……………………………………………………………………………………………..
……………………………………………………………………………………………..
……………………………………….
75