ICT
What is ICT?
• ICT stands for Information and
Communications Technology.
• Two technologies make up ICT, and these are:
– Information Technology
– Communications Technology
What is Information Technology?
• IT is a combination of facilities for collecting,
storing, retrieving and processing of information.
• IT can be manual or electronic.
• The major component of electronic information
technology is the computer.
• Electronic information technology has many
advantages as compared to manual information
systems.
What is Communications Technology?
• Communications Technology is a collection of
facilities for transmission and reception of
information.
• Communications Technology can be manual or
electronic.
• The major components of electronic
Communications Technology are computers
and telecommunications facilities.
What does one learn in ICT?
• How to collect, store, retrieve and process
data.
• How to transmit and receive information.
• How to identify and correct errors during
processing or transmission.
• How to identify, install and troubleshoot ICT
facilities.
ECONOMIC BENEFITS OF COMMPUTERS
• These are financial savings that are attributed
to the use of computers, e.g.
– Reduction in the time of processing data.
– Reduction in the cost of storage facilities.
– Reduction in the number of staff employed to do
routine tasks
ADVANTAGES OF COMPUTERS
• They are fast – work can be accomplished
within a very short time.
• They are very accurate and consistent – work
can be done with almost no errors.
• They reduce most operating costs.
• They lead to improved customer service.
• They can be used to automate tedious,
routine and repetitive tasks.
ADVANTAGES OF COMPUTERS
(Continued)
• They can be used to do or monitor work in
inaccessible places, e.g. high temperature
furnaces and nuclear reactors.
• They can be linked in networks for the
purposes of communication and sharing
resources, e.g. data, hardware and software.
• They can enable co-workers to collaborate on
tasks.
ADVANTAGES OF COMPUTERS
(Continued)
• They can make complex calculations easier.
• They can be used to gain competitive
advantage in business.
• They can work for very long periods without
requiring rest and remuneration.
LIMITATIONS OF COMPUTERS
• Computers have limitations, i.e. they cannot be
expected to do everything.
• Their limitations are due to the fact that they are
programmed machines.
• As programmed machines, they can only manage to
do work which is specified in their programs.
• Computers cannot be used to perform new tasks
whose programs have not been made and installed.
HOME WORK
Some people believe that
computerising operations of an
organisation always leads to
unemployment. This belief is not
exactly correct. Give details to show
that this belief is based on biased
conclusions.
COMPUTER-RELATED CRIME
• Computers can also be used to perpetuate and
perpetrate various forms of crime.
• Examples of computer-related crimes are:
– Piracy of intellectual property, e.g. software, music and
video.
– Unauthorized access to information through methods such
as identity theft.
– Pornography.
– Virus attacks.
– Harassment and victimization.
– Theft or destruction of data.
IMPORTANCE OF ICT IN
EDUCATION
• ICT is important in education for many
reasons.
• It is important to education authorities, e.g.
educational planners and education
administrators.
• It is important to teachers and students.
IMPORTANCE OF ICT TO EDUCATION
ADMINISTRATORS
• Processing and storage of information
required for decision making and other
management functions such as:
– Controlling
– Coordinating
– Forecasting
– Organizing
• Efficient communication with schools,
partners, sponsors and parents.
IMPORTANCE OF ICT TO TEACHERS
• Teachers can use ICT in many ways, e.g.
• Processing and storage of assessment
instruments, e.g. assignments, tests and
examinations.
• Processing and storage of students records.
• Research and development of teaching
resources.
• Communication with students and school
managers.
IMPORTANCE OF ICT TO STUDENTS
• Students can also use ICT in many ways, e.g.
• Research for study materials, e.g. use of the
Internet.
• Communication with teachers, sponsors, parents
and friends.
• Production of learning resources, e.g. notes and
assignments.
• As a tool for self-paced learning, e.g. use of audio,
video and virtual classrooms.
CLASSIFICATION OF COMPUTERS
• There are various classes of computers.
• It is important to understand the various
classes of computers for a number of reasons,
e.g.
– Different computers are used for different
purposes.
– Different computers have different processing
power.
– Different computers have different costs.
– Different computers require different operating
conditions.
CLASSIFICATION OF COMPUTERS
• Computers can be classified on the basis of
many factors, e.g.
– Cost
– Speed of processing
– Amount of storage
– Operating environment
– Physical size
CLASSIFICATION OF COMPUTERS
• On the basis of the factors outlined above,
computers are classified as follows:
– Microcomputers
– Servers
– Minicomputers
– Mainframe computers
– Supercomputers
CLASSIFICATION OF COMPUTERS
• Microcomputer
CLASSIFICATION OF COMPUTERS
• Server Computer
CLASSIFICATION OF COMPUTERS
• Minicomputer
CLASSIFICATION OF COMPUTERS
• Mainframe Computer
CLASSIFICATION OF COMPUTERS
• Supercomputer
CLASSIFICATION OF COMPUTERS
• MICROCOMPUTERS
– They are the most widespread.
– They are also called personal computers because
of being single user.
– They include the following:
•
•
•
•
•
Desktops
Laptops
Notebooks
Netbooks
Palmtops
MICROCOMPUTERS
• Desktop Computers
MICROCOMPUTERS
• Laptop Computer
MICROCOMPUTERS
• Notebook Computer
MICROCOMPUTERS
• Netbook Computer
MICROCOMPUTERS
• Palmtop Computer
WHY MICROCOMPUTERS ARE THE
MOST COMMON
•
•
•
•
•
•
They are portable.
They cost the least amount of money to buy.
They use less sophisticated software and hardware.
They can be upgraded easily.
They do not necessarily require air-conditioned rooms.
Their processing power can be increased by
connecting them in a network.
UNDERSTANDING A COMPUTER
What is a computer?
• A computer is a machine that performs tasks such as
calculations or electronic communication under the
control of a set of instructions called a program.
• Every computer does the following:
– Accepts data and instructions
– Stores the data and the instructions
– Retrieves data
– Processes data using the stored instructions
– Gives feedback or results in any desired format
UNDERSTANDING A COMPUTER
(Continued)
• Strictly, a computer is not one item.
• A computer is a collection of different facilities which
all work together to accomplish a task.
• Therefore, a computer is a system.
• Generally, a computer consists of two main parts.
• The main parts that make up a computer are
hardware and software.
• Therefore, Computer = Hardware + Software
SOME UNITS OF A DESKTOP COMPUTER
SYSTEM
COMPUTER HARDWARE
• Computer hardware is the physical part of a
computer.
• It consists of everything that can be touched,
felt or seen.
• In general, computer hardware resources are
in four categories as follows:
– Input
– Processor
– Storage
– Output
COMPUTER HARDWARE
(Continued)
.
INPUT
PROCESSOR
OUTPUT
STORAGE
Arrows show the flow of data within the
computer.
COMPUTER HARDWARE
(Continued)
• One of the functions of the processor is to
direct the performance of all the other
computer units.
• The processor does this by issuing specific
instructions to the other units indicating what
and how they must do it.
• The flow of instructions from the processor is
as shown in the diagram below.
COMPUTER HARDWARE
(Continued)
• Instructions from the processor
INPUT
PROCESSOR
STORAGE
OUTPUT
INPUT DEVICES
• Input devices are used to capture data into the
computer.
• Input devices are also used for entering commands.
• Commands are instructions that users give to the
computer to initiate them into action.
• Since the computer’s processor can only understand
and do things in machine language, an input device is
used to convert data from human language to
machine language.
Examples of input devices
Keyboard
Game
controller
Scanner
Mouse
Track ball
Camera
Joystick
Microphone
Examples of input devices
Touch Screen
Bar code Reader
Drawing Tablet
KEYBOARDS
• A keyboard's primary function is to act as an input
device.
• A keyboard is used to enter both data and
commands into the computer.
• Using a keyboard, a person can type a document, use
keystroke shortcuts, access menus, play games and
perform a variety of other tasks.
• Keyboards can have different keys depending on the
manufacturer, the operating system they are
designed for, and whether they are attached to a
desktop computer or part of a laptop.
KEYBOARDS
(Continued)
• There are different types of keyboard as
illustrated below.
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
KEYBOARDS
(Continued)
MACHINE LANGUAGE
• Machine language is a programming language that
can be understood directly by a computer’s central
processing unit.
• Machine language consists of codes of characters in
binary.
• Binary is a number system in base 2.
• In machine language, characters are represented by
bits (i.e. binary digits) consisting of ones (1) and
zeros (0).
• For example, in a coding scheme called ASCII, A is
01000001, B is 01000010.
MACHINE LANGUAGE
(Continued)
• A binary representation of a character
represents the type of current that must flow
when the character is being entered from the
input to the processor.
• Each 1 in the code represents high current,
and each 0 represents low current.
• For a code 101010101, the current has the
wave form
MACHINE LANGUAGE
Character
A
B
C
D
E
ASCII Code Current
01000001
01000010
01000011
01000100
01000101
(Continued)
EXERCISE
• Write the ASCII codes and the corresponding
current wave forms for F, G, and H.
OUTPUT DEVICES
• An output device is used to give feedback to
the user.
• Since the CPU does work in machine language
which is not understood by human beings, the
results from the CPU have to be converted
into human readable form by the output.
Examples of output devices
CRT Monitor
DeskJet Printer
LCD Monitor
Impact Dot Matrix Printer
LaserJet Printer
Speakers
Examples of output devices
Plotter
(Continued)
Examples of output devices
Plotter
(Continued)
CRT MONITORS
• They have the cathode ray tube.
CRT MONITORS
(Continued)
Advantages:
• They are cheaper than LCD monitors.
• They are easy to repair.
Disadvantages:
• They occupy a lot of space on the desk.
• They consume a lot of electrical energy.
LCD MONITORS
• They have liquid molecules.
Advantages:
• They occupy less space on the desk.
• They consume less electrical energy than CRT
monitors.
Disadvantages:
• They cost more money.
• They are not easily repaired when they develop
faults.
IMPACT DOT MATRIX PRINTERS
• They have a knob for advancing paper.
• They use an inked ribbon.
• They print by striking a pattern of dots on
paper through the inked ribbon.
IMPACT DOT MATRIX PRINTER
(Continued)
Advantages:
• They can be used with carbon paper to print multiple
copies at once.
• Their ribbons are not very expensive.
• They are durable.
• They are excellent for high volumes of printing where
high quality is not essential.
• The ribbons fade gradually instead of abruptly
running out of ink like in a deskjet printer.
• The ribbon does not dry out easily, so the print looks
good even if the printer is rarely used.
• They can use fanfold paper, i.e. paper that is
connected in a long continuous sheet.
IMPACT DOT MATRIX PRINTER
(Continued)
Disadvantages:
• They are very slow; they print one line or one
character at a time.
• They make so much noise when printing.
• Print heads are difficult to replace when they get
worn out.
• Their printout has low quality.
• They can print in black only.
• They are more prone to jamming, and their jams are
more difficult to clear.
DESKJET PRINTERS
DESKJET PRINTERS
(Continued)
• They use ink to print.
Advantages:
• They can print in colour.
• They are less expensive to buy.
• They make less noise when printing.
• They are very light; some are portable.
• Their printout has good quality.
DESKJET PRINTERS
(Continued)
Disadvantages:
• Their ink is expensive.
• They cannot be used with carbon paper.
• Their ink runs when touched with wet hands.
• Sometimes inkjet cartridges get clogged with
dirty which either blocks the ink droplets or
causes them to land incorrectly.
LASER JET PRINTERS
LASER JET PRINTERS
• They use toner and laser light.
Advantages:
• They print very fast.
• They print more quietly.
• They can print in colour or black.
• Their printout is of high quality.
(Continued)
LASER JET PRINTERS
(Continued)
Disadvantages:
• They are expensive to buy.
• Their toner is costly as well.
• They use laser light which is harmful when
exposed to it.
• They consume more electrical energy.
RESOLUTION OF AN OUPUT DEVICE
• Resolution refers to the sharpness or clarity of an
output.
• Often resolution is quoted in dots per inch (dpi), i.e.
…..
• The higher the resolution of an output device, e.g. a
monitor or a printer, the better the quality of the
output.
• Among the printers, the laser jet printer gives the
highest resolution, and the impact dot matrix printer
the lowest.
STORAGE DEVICES
• Why does a computer require storage?
– To store user data.
– To store computer programs.
• There are three types of storage devices.
• The three types are magnetic devices, optical
devices and semiconductor devices.
MAGNETIC STORAGE DEVICES
• These use magnetic properties to store data.
• To make a storage device, a magnetic powder,
e.g. iron oxide, is coated on a material.
• Data is stored by forming a magnetic pattern
on the powder, similar to the way music is
recorded on audio tapes.
MAGNETIC STORAGE DEVICES
(Continued)
• There are two types of magnetic storage
devices:
• The two types are magnetic tapes and
magnetic disks.
• Magnetic tapes are used very rarely nowadays
because they are slow.
• There are two types of magnetic disk.
MAGNETIC DISKS
• The two types of magnetic disk are floppy disk
and hard disk.
• The hard disk stores more data than the
floppy disk.
• The hard disk is made from hard material such
as aluminium.
• The floppy disk is made from soft material, i.e.
plastic.
MAGNETIC DISKS
(Continued)
• Floppy disks are no longer popular on modern
computers.
• Floppy disks are removable from the
computer because they must be removed as
you shut down.
• Hard disks are ‘fixed’ in the computer because
they are not removed as you shut down.
• However, external hard disks can be removed
from the Computer.
OPTICAL DISKS
• Optical disks do not use magnetic properties
to store data.
• Optical disks use laser light to store data on
storage medium.
• Examples of optical disks are CDs, CD-ROMs,
and DVD-ROMs.
• Optical disks store more data than floppy
disks.
SEMICONDUCTOR STORAGE
• A semiconductor storage device does not use
magnetism or light to store data.
• Semiconductor storage devices use electronic
chips to store data.
• An example of a semiconductor storage device
is a flash disk.
• Flash disks store more data than floppy disks,
and they are easier to carry.
• Some flash disks store more data than CDROMs and DVD-ROMs.
Examples of Storage Devices
Hard Disk
Zip Disk
Floppy Disk
Flash Disk
CD-ROM
External Hard
Disk
Examples of Flash Disks
STORAGE CAPACITY
• The storage capacity of a storage medium is
given in BYTES.
• One byte of data is equal to eight bits.
• For example, in a coding system called
Extended Binary Coded Decimal Interchange
Code (EBCDIC), the letter A is represented by
11110001.
• 11110001 is one byte.
STORAGE CAPACITY
•
•
•
•
•
•
•
•
(Continued)
1kilobyte (kB) means one thousand (210) bytes
1megabyte (MB) means one million (220) bytes.
1gigabyte (GB) means one billion (230) bytes.
1terabyte (TB) means one trillion (240 ) bytes.
1petabyte (PB) means one quadrillion (250) bytes.
1exabyte (EB) means one quintillion (260) bytes.
1zettabyte (ZB) means one sextillion (270) bytes.
1 yottabyte (YB) means one septillion (280) bytes.
EXERCISE
1. How many bits make up one character?
2. How many characters can a 512MB flash disk
hold?
3. How many bits can a 160GB hard disk hold?
4. What is the difference between 20b and
20B?
DISK DRIVES
• In the computer, a disk (floppy, hard or
optical) is controlled by a mechanism called a
disk drive.
• Disk drives are identified by letters A, B, C, D,
and so on.
• Disk drives A and B are no longer used on
modern computers because they are for
floppy disks which have become obsolete.
DISK DRIVES
(Continued)
DISK DRIVES
(Continued)
• Disk drive C is always for the first hard disk which was
installed.
• If a computer has two hard disk drives, the first is C and the
second is D.
• A computer denotes a flash disk as a removable disk.
• For a computer with one hard disk drive, flash disks are
assigned letters D, E, F, G, and so on.
• To check how many and which drives a computer has, you
simply open the My Computer or Computer folder on the
Windows Desktop.
THE PROCESSOR
• This is the most important part of computer
hardware.
• It has many parts that perform different
functions.
• The most fundamental parts of the processor
are as follows:
 Control Unit – CU
 Arithmetic and Logic Unit – ALU
 Random Access Memory – RAM
 Read Only Memory – ROM
THE PROCESSOR
.
PROCESSOR
CPU
CU
ALU
OUTPUT
INPUT
RAM
ROM
STORAGE
MAIN MEMORY
THE CONTROL UNIT – CU
• Controls all functions of the computer, e.g.
– Controlling operations of input/output (i/o)
systems.
– Controlling movement of data in the
computer.
– Configuring and optimizing RAM to ensure
that it works efficiently.
THE ALU
• This is the unit that does the actual processing of
data.
• It processes data by doing arithmetic and logic
operations.
• Arithmetic means addition, subtraction, multiplication
and division.
• Logic is comparing things so as to make appropriate
choices.
• The CU and the ALU are made on the same computer
chip called the Central Processing Unit (CPU) or the
microprocessor.
RAM
• RAM is temporary storage.
• When power is switched off, everything is erased
from RAM.
Functions of RAM include the following:
– Receiving raw data from input.
– Receiving processed data from the ALU.
– Storing instructions required by the CU.
– Holding data awaiting output.
– Holding data awaiting storage.
ROM
• ROM stores instructions that are used to start the computer.
• Instructions in ROM cannot be erased.
• During startup, the computer follows instructions in ROM to do
the following:
– Read the amount of RAM present.
– Check that monitor, keyboard and mouse are connected and
working.
– Check that components on the motherboard are working
properly.
– Check that the hard disk drive is connected and working.
– Load the operating system software in RAM from storage.
THE BIOS
• BIOS stands for Basic Input/Output Systems.
• Every computer has specifications such as hard disk
size, memory size, and processor speed.
• A bios is a unit (usually part of the ROM) which keeps
these specifications.
• During booting, the computer uses instructions in the
ROM to check that these parameters are correct.
• Together, ROM and BIOS are called ROM-BIOS.
BASIC UNDERSTANDING OF PROGRAM EXECUTION
• The main function of the CPU is to execute, i.e. to
run, a program.
• A program consists of several instructions , or
steps.
• Each instruction tells the computer to perform a
specific task.
• A program is executed one instruction at a time.
• Initially a program is loaded in RAM.
• The CU, the ALU and the RAM coordinate very
closely during program execution.
HOW CU, ALU AND RAM WORK TOGETHER
• CU fetches an instruction from RAM and puts it in its CIR
(i.e. Current Instruction Register).
• CU decodes, i.e. interprets the instruction and
communicates with ALU.
• CU directs RAM to send data to ALU.
• ALU processes data and places the processed data in its
ACCUMULATOR.
• CU directs ALU to send processed data back to RAM.
• CU directs RAM to send processed data to Output or
Storage.
• Current Instruction Register and Accumulator are examples
of Registers found in the CPU.
EXERCISE
1. What is the main function of the CPU?
2. Name two things which the CPU always
fetches from RAM.
3. What is the use of the CIR?
4. In which unit do we find the accumulator,
and what is the function of the accumulator?
REGISTERS OF THE CPU
• The CPU has a number of registers.
• Registers are temporary storage locations.
• Registers are used because they work faster
than RAM.
• Because within the CPU data and instructions
must be transferred very quickly, the CPU
places current instructions and data in the
registers.
REGISTERS OF THE CPU
(Continued)
• Some of the registers of the CPU are:
1. Current Instruction Register (CIR) in the CU and is
used to hold an instruction being obeyed to
process data.
2. Memory Data Register (MDR) in the CU used to
hold data currently being processed.
3. Accumulator in the ALU and is used to hold data
that has just been processed.
4. Memory Address Register (MAR) in the CU used to
hold the address of data being processed.
COMPUTER BUSES
• Buses are routes through which data and instructions
travel from one point to another in the computer.
• The processor has many buses that convey different
signals.
• The capacity of a computer is also determined by the
size of its buses.
• The greater the bus, the faster the computer because
many signals can be transferred at the same time.
PROCESOR BUSES
(Continued)
• Examples of buses in the computer are:
1. Data Bus which carries data signals between
the CPU and RAM.
2. Address Bus which carries addresses of data
between the CPU and RAM.
3. Control Bus which carries control signals
from the CPU to all other units.
COMPUTER SOFTWARE
• Computer hardware requires software to tell it
what to do and how to do it.
• A computer consists of many, many different
types of software.
• Every software has a specific purpose in the
computer.
• Computer software is in three types – Systems
software, Utility software, and Applications
software.
SYSTEMS SOFTWARE
• Systems software is the software used by the
computer to accomplish general functions.
• Systems software is the most important software
because without it the computer cannot do anything.
• Systems software consists of several classes of
software.
• One of the classes is the operating system.
OPERATING SYSTEM
• This is the most important type of software in a
computer.
• It is referred to as the manager, the supervisor or the
chief executive in the computer
• It is the one that tells the hardware what to do and
how to do it.
• For example, it controls the printer during printing of
documents.
• It also interprets the user’s commands.
• It acts as an interface, i.e. as a link, between
applications software and the hardware.
• It directs the flow of data between input and output
systems.
EXAMPLES OF OPERATING SYSTEMS
There are many operating system programs, e.g.
• Microsoft Windows
–
–
–
–
–
–
–
–
Windows 95
Windows 98
Windows NT
Windows Millennium
Windows 2000
Windows XP
Windows Vista
Windows 7
• Unix
• Linux
• MacOS
UTILITY SOFTWARE
• Utility software is used by the computer to
accomplish specific tasks.
• Examples of utilities are:
– Antivirus software, e.g. Norton, Dr. Solomon, McAfee,
AVG, Panda, Avast - for checking and protecting a
computer against viruses.
– Scandisk - for checking the integrity of disks.
– Disk Defragmenter - for correcting disks that have become
fragmented.
– Device drivers - for effecting communication between
input/output units, (e.g. keyboard, mouse, monitor,
printer) and the CPU.
DEVICE DRIVERS
• These are computer programs that are used to
control the performance of devices in the
computer.
• Every device, e.g. keyboard, mouse, monitor,
printer, etc has a specific software that
controls it.
• If a device driver for a particular device is
missing or damaged, that device will not work.
APPLICATIONS SOFTWARE
• This is software in a computer which users employ to
do their work.
• Whereas a computer may have one Operating
System software, it always has several Applications
software, all being serviced by the same Operating
System.
• Applications software interacts with users directly –
it is the one which knows how to manipulate data
the way the user wants it to be.
• It does not have the capacity to control or interact
with the hardware directly.
EXAMPLES OF APPLICATIONS SOFTWARE
• Word processors, e.g. Microsoft Word,
Amipro, WordStar, WordPerfect.
• Spreadsheets, e.g. Microsoft Excel, Lotus.
• Databases, e.g. Microsoft Access, Paradox,
dBase 7.
• Financial analysis software, e.g. Pastel.
• Payroll software, e.g. MicroPay
• Computer games
STARTING THE COMPUTER
• Locate the power switches on the system unit
(or CPU) and on the monitor.
• Switch on the monitor.
• Switch on the system unit.
• Wait for the computer to be ready.
Starting a computer is also called BOOTING.
MICROSOFT
WINDOWS
INTRODUCTION
• Microsoft Windows is an operating system
software.
• As an operating system, it directs and
monitors the operation of the computer.
• As an operating system, it makes it possible
for the user to use the computer with less
effort.
• Thus it makes a computer to be an automatic
machine.
Windows Desktop
This is the screen that you come to when you
start Microsoft Windows.
Parts of Windows Desktop
Icons
START button
Open Program or Document
Desktop background
Task Bar
Clock
Computer Mouse
Right button
Scroll Wheel
Left button
•
•
A mouse is a pointing device.
It is used to move a pointer on the screen.
Pointing, Clicking and Double-clicking
• Pointing is moving a pointer on the screen so
that its tip is placed on a chosen area or spot.
• Clicking is pressing and releasing a mouse
button.
• Double-clicking is pressing and releasing a
mouse button twice in rapid succession.
• Clicking is used to select an item.
• Double-clicking is used to start something, e.g.
to open a program, a folder or a file.
Parts of a Window
Title bar
Minimize button
Restore button
Close
button
Menu bar
Address
box
Scroll
button
Scroll bar
Icons
Functions of parts in a window
• Title bar
– Used to display the name of the open window.
– Used to move or drag a window.
• Minimize button
– Used to minimize a window so that only its name
is visible on the Taskbar.
• Maximize button
– Used to maximize a window so that it fills the
whole screen.
Functions of buttons in a window
(Continued)
• Restore down button
– Used to return the window to the original size
before it was maximized.
• Close button
– Used to close a window.
The Menu Bar
• A menu is a list of command options in a
computer.
• The menu bar is found just below the Title bar.
• It shows the different menus present in a
window.
• Examples of menus are File, Edit, View, Tools,
and Help.
Closing a window
• You can close a window in two ways:
1. Click the Close button, or
2. - Click File menu
- Point to Exit and click
Moving a window
•
A window can be moved from place to place on the
desktop.
• Ensure that the window is not maximized or
minimized before you start the procedure.
1. Point to the Title bar of the window. (Ensure that it
does not change shape.)
2. Hold down the left mouse button and drag the
window to another place.
3. Release the mouse button.
Re-sizing a window
•
You can change the size of a window by
doing the following:
1. Point to the edge of the window until the
pointer becomes a double-headed arrow.
2. Hold down the left mouse button and drag
the edge to a new position.
3. Release the mouse button.
Scroll bar
• If the window has so many items that they
cannot all be visible, a scroll bar appears.
• A scroll bar is either horizontal or vertical.
• There is always a scroll button on the scroll
bar.
• To scroll your window, drag the scroll button in
an appropriate direction.
My Computer
It is a window which shows the disk drives
connected to your computer.
My Documents
It is a window which contains the documents
or files that you save in your computer.
Recycle bin
It is a window which contains documents or
folders that you have removed from your
computer.
Control Panel
It is a window you use to customize the
appearance and functionality of your computer.
CUSTOMIZING THE COMPUTER
• This is setting the computer so that it appears
and behaves the way you want.
• You use Control Panel to customize the
computer.
• Using Control Panel you can customize the
mouse, the keyboard, the printer, the monitor,
e.t.c.
CUSTOMIZING WINDOWS DESKTOP
•
•
•
•
Click on the START button.
Click on Control Panel.
Click on Appearance and Themes.
Select what you want to customize, e.g.
– Change the computer’s theme
– Change the desktop background
– Choose a screen saver
– Change the screen resolution
Folders
•
Folders are used like box files or File cabinets.
•They are used for organizing documents.
• A folder can have another folder inside it.
• A folder found inside another folder is called a
sub-folder.
• Folders can be made in any storage location, e.g.
hard disk, floppy disk, flash disk, or inside another
folder.
Making Folders
Do the following to make a folder:
1. Open the place where you want to make the
folder.
2. Click File menu.
3. Point to New and click Folder.
4. Type the name of the folder and either press
the Enter Key or click outside the name you
have typed.
WordPad
• WordPad is a word processor found within
Microsoft Windows.
• A word processor is a kind of computer
software for creating and editing documents.
WordPad
STARTING WordPad:
• Click the START button on the Task bar.
• Check on the Start Menu for WordPad and
click on it if you see it. If you don’t see
WordPad, proceed as outlined below.
1.Point to All Programs.
2.Point to Accessories.
3.Move to WordPad and click on it.
Title bar
Formatting bar
WordPad
Menu bar
Standard Toolbar
WordPad
SAVING A DOCUMENT IN WordPad:
• Saving is transferring work from the computer’s
memory, i.e. RAM, to the computer’s storage.
• To save your work in WordPad or in any program, do
the following:
1.
2.
3.
4.
Click File Menu.
Click Save As…
Open the place in which you want to save the work.
Click in the File Name box and erase any name you find
there.
5. Type the name you want to use for your document.
6. Click Save.
Opening a saved document in
WordPad
• Start WordPad.
1.Click File Menu.
2.Click Open.
3.Open the storage location where the
document was saved.
4.Click in the File Name box and type the name
of the document.
5.Click the Open button.
•
•
•
•
•
COPYING AND MOVING FILES AND
FOLDERS
Open My Documents.
Open the storage location where the file or folder is.
Right click the file or folder.
Left click Copy (to copy file) or Cut (to move file).
Open the storage location where you want to place
what you have copied or cut.
• Right click some where.
• Left click Paste.
MICROSOFT WORD
• What is Microsoft Word?
• Microsoft Word is a word processing software.
• A word processing software is used for typing,
formatting and editing word documents.
• Word documents are documents that contain
mainly text information.
• Word Processors are the most popular software
because they are easier to use and almost
everyone always wants to communicate text
messages with other people.
MICROSOFT WORD
Starting Microsoft Word
• Do one of the following to start Microsoft
Word:
– Look for the Microsoft Word icon on the desktop
and double click it.
– Click the Start button, look for Microsoft Word on
the Start Menu and click it.
– Click the Start button, point to All Programs, point
to Microsoft Office, point to Microsoft Word and
click.
THE MICROSOFT WORD WINDOW
• The Microsoft Word window has the usual
features of a window, i.e. Title bar, Menu bar
and tool bars.
• The toolbars in Microsoft Word have tools for
doing word processing.
• Examples of the popular toolbars are Standard
Toolbar, Formatting Toolbar and Drawing
Toolbar.
THE MICROSOFT WORD WINDOW
Title bar
Menu bar
Standard Toolbar
Drawing Toolbar
Formatting Toolbar
CUSTOMIZING MICROSOFT WORD WINDOW
• You can customize the Microsoft Word by
removing or adding toolbars or by changing
the colour of the work area.
• To add or remove toolbars do the following:
– Click the View menu.
– Point to Toolbars
– Click on the name of the toolbar to remove a
check mark or to add a check mark.
CUSTOMIZING MICROSOFT WORD WINDOW
To change the background colour of the window,
do the following:
• Click the Format menu.
• Point to Background and click the colour on
the colour palette you want to apply.
TYPING A DOCUMENT IN MICROSOFT WORD
• Start Microsoft Word.
• Ensure that you have the Standard Toolbar,
the Formatting Toolbar and the Drawing
Toolbar present.
• Start typing your text.
• Press the Space bar to put spaces between
words.
• Press the Enter key to start a new paragraph.
MICROSOFT WORD
Formatting a document:
• This means making changes to parts of a document
in order to improve its quality.
• Examples of formatting are:
–
–
–
–
–
–
–
–
–
Bold
Italics
Underline
Changing font type and size
Aligning
Indenting
Changing colour of text
Line spacing
Bulleting
MICROSOFT WORD
To format text in a document:
1. Highlight the text you want to format.
2. Click the appropriate formatting toolbar icon
on the formatting bar.
3. Click any where outside the highlighted area
to remove the highlight.
MICROSOFT WORD
Editing a document
• This means making changes by removing or
adding text at appropriate points in the
document.
• Examples of editing are:
– Copy and paste
– Cut and paste
– Undo
– Re-do
MICROSOFT WORD
Using Undo and Redo
• Undo reverses the changes made to a
document.
• Redo reverses the changes done by Undo.
• Click the Undo icon on the Standard Toolbar
to reverse your action.
• Click the Redo icon on the Standard Toolbar
to reverse the changes made by Undo.
MICROSOFT WORD
Using Format Painter
• Format Painter is a tool used to apply the
formats from one part to another part of a
document.
• Highlight the part that has the formats you
want to apply to another part of your
document.
• Click the Format Painter icon on the Standard
Toolbar
MICROSOFT EXCEL
MICROSOFT EXCEL
• What type of software is Microsoft Excel?
• Microsoft Excel is a type of software called
spreadsheet.
• A spreadsheet is a software program for
performing calculations, analyzing and
managing lists of data.
• Another popular spreadsheet program is
Lotus.
STARTING MICROSOFT EXCEL
•
•
•
•
Click the START button on the Task bar.
Point to All Programs.
Point to Microsoft Office.
Move the pointer to Microsoft Excel and click
on it.
THE MICROSOFT EXCEL WINDOW
• In general, the Microsoft Excel window looks
like any other window in Microsoft Windows.
• The Microsoft Excel window has
– The Title bar
– The Menu bar
– The Standard Toolbar
– The Formatting Toolbar
– The Drawing Toolbar
BASIC FEATURES OF MICROSOFT
EXCEL
• As a spreadsheet, Microsoft Excel has the
following basic features:
– Workbooks - This is a file that contains one or
more worksheets.
– Worksheets – Data in a workbook is organized in
worksheets.
– A workbook is like your notebook, and a
worksheet is like pages in your notebook.
BASIC FEATURES OF MICROSOFT
EXCEL
• A worksheet consists of Rows and Columns.
• Rows are identified by the numbers on the left
side of the worksheet.
• Columns are identified by letters at the top of
the worksheet.
• The intersection of a row and a column is
called a CELL.
CELL REFERENCES
• Every cell in a spreadsheet has a unique
reference or address.
• The cell reference or address is specified by
stating its column letter and row number, e.g.
A1, B25, R54.
• The name of the current cell is displayed in
the NAME BOX.
CURRENT CELL
• A rectangular box that moves from one cell to
another in a worksheet is called a CELL
POINTER.
• The cell where the Cell Pointer is at any time is
called the CURRENT CELL.
• In a worksheet, data is always entered in the
current cell.
FORMULA BAR
• The FORMULA BAR is located just above the
columns header row.
• The Formula Bar displays data entered in the
current cell.
• The Formula Bar is also used to edit data
entered in any cell.
MOVING THE CELL POINTER
• To move the cell pointer in a worksheet, do
one of the following:
– Click the cell you want the cell pointer to move to.
– Use one of the Arrow Keys on your keyboard to
take the cell pointer to the required cell.
TYPES OF WORKSHEET DATA
• You can enter three types of data in a
worksheet.
• The three types of worksheet data are:
– Labels
– Values
– Formulas
LABELS
• Labels are used to give meaning to values in a
worksheet.
• An entry such as 67% does not make sense
unless we attach a label to state what it
means.
• Any data entry which contains an alphabet
character is a label.
• Labels are aligned left in cells, e.g.
TVTC
VALUES
• Any numeric data entered in a cell is called a
value.
• Values are aligned right in cells, e.g.
200
FORMULAS
• Formulas are used to calculate values.
• A formula is entered starting with the EQUALS
(=) sign.
• If the equals sign is not used, Microsoft Excel
looks at the entry as a label.
• Example of a formula is =A3-A4 or
=(A5-C8)/23.
ENTERING DATA IN CELLS
• Select the cell in which you want to enter the
data.
• Type in the data.
• Press Enter or move to another cell using one
of the arrow keys.
• At the end of the row, press ENTER to move to
the beginning of the next row.
ENTERING DATA INTO SEVERAL CELLS
AT ONCE
• Select the cells where you want to enter data.
The cells do not have to be adjacent.
• Type the data and press CTRL+ENTER.
FILLING IN A SERIES OF DATA
•
•
•
•
Select the first cell in the range you want to fill.
Enter the starting value for the series.
Enter a value in the next cell to establish a pattern.
Select the cell or cells that contain the starting
values.
• Drag the fill handle over the range you want to fill.
• To fill in increasing order, drag down or to the right.
• To fill in decreasing order, drag up or to the left.
CHANGING COLUMN WIDTH AND
ROW HEIGHT
• Drag the boundary on the right side of the column
heading until the column is the width you want.
• For multiple columns, select the columns you want
to change, and then drag a boundary to the right of a
selected column heading.
• To fit the contents in a cell, double-click the
boundary to the right of the column heading.
CHANGING COLUMN WIDTH AND
ROW HEIGHT
• To resize a row height, drag the boundary
below the row heading until the row is the
height you want.
• To resize multiple rows, select the rows you
want to change, and drag a boundary below a
selected row heading.
• To fit the contents in a cell, double-click the
boundary below the row heading.
EDITING DATA IN CELLS
• Double-click the cell that contains the data
you want to edit.
• Edit the cell contents.
• To enter or cancel your changes, press ENTER
or ESC.
COPYING AND MOVING DATA
• To copy data, select the cells that contain the
data you want to copy.
• Click the COPY icon on the Formatting Toolbar.
• Click in the first cell of the range to copy data
to.
• Click the Paste icon on the Formatting Toolbar.
• Press ENTER.
COPYING AND MOVING DATA
• To move data, select the cells that contain the
data you want to move.
• Click the CUT icon on the Formatting Toolbar.
• Click in the first cell of the range to move data
to.
• Click the Paste icon on the Formatting Toolbar.
• Press ENTER.
COPYING CELL FORMATS
•
•
•
•
•
•
Select the cells you want to copy.
Click Copy on the Standard Toolbar.
Select the upper-left cell of the paste area.
Click the arrow to the right of Paste, and
click Paste Special.
Click Formats.
Press Enter.
USING FORMULAS
• Formulas are equations that perform
calculations on values in your worksheet.
• A formula starts with an equal sign (=).
• For example, the following formula multiplies
5 by 6 and then adds 20 to the result.
• =20+5*6
USING FORMULAS
• To use a formula do the following:
• Click the cell in which you want to
enter the formula.
• Type = (an equal sign).
• Enter the formula.
• Press ENTER.
USING FORMULAS
•
•
1.
2.
3.
4.
5.
6.
7.
Worksheets usually contain massive amounts of related
data.
For example, a business may create a worksheet with the
following details:
Names of products purchased.
Cost price of products purchased.
Quantity of products purchased.
Cost of all products.
Selling price of products.
Revenue gained by selling all products.
Profit gained from the products.
USING FORMULAS
• Simple formulas have disadvantages.
• This is because they have to be entered many
times to calculate different values.
• Formulas based on the cell references are
better.
• For example, if 20 is in cell A1, 5 in cell B1 and
6 in cell C1, it is better to enter a formula as
=A1+B1*C1 instead of =20+5*6 in cell D1.
USING FORMULAS
• The advantage of using formulas that contain
references is that if you change a value in one
cell, changes are automatically effected in all
formulas that contain the affected cell.
EXERCISE
• Enter 20 in cell A1, 5 in cell B1 and 6 in cell C1.
• Click in cell D1.
• Type the simple formula: = 20+5*6 and press
ENTER.
• Click in cell E1.
• Type the formula: =A1+B1*C1 and press
ENTER.
• Click in cell B1, type 7 and press ENTER.
• Compare the effects of the two formulas.
AUTOMATING CALCULATIONS
• Enter the following data in a worksheet.
• Calculate the amount for each product.
• Calculate the TOTAL amount for all products.
AUTOMATING CALCULATIONS
•
1.
2.
3.
4.
5.
Instead of repeating the calculation for the
AMOUNT for every product, do the following:
Click in cell D2 and enter the formula =B2*C2.
Click in cell D2 again.
Place the mouse pointer on the Fill Handle at the
bottom right corner of the Cell Pointer.
Drag down to cell D6 and release the mouse
button.
Click in cell D7 and enter the formula: =Sum(D2:D6)
to calculate the TOTAL amount.
SORTING DATA
• Sorting data means presenting data so that it
has either an ascending or a descending
order.
• To sort data, do the following:
• Highlight the range of cells to sort (include the
row headings).
• Click the Data menu.
• Select the required sort order.
• Click OK.
TOTALS AND SUBTOTALS
•
Suppose that you order various products for
re-sale in your shop in a particular week or
month.
• At the end of the period you may want to
find the following information:
1. The amount of money spent on each type of
product.
2. The total amount of money spent on all the
products.
TOTALS AND SUBTOTALS
• EXERCISE
1. Enter your data as shown below:
TOTALS AND SUBTOTALS
2.
3.
4.
5.
6.
Click in cell E2.
Type =Sum(E2:E16)
Press ENTER.
Click in cell E2 again.
Place the mouse pointer on the Fill Handle at the bottom
right corner of the Cell Pointer.
7. Drag down to cell E16 and release the mouse button.
8. Click the DATA menu and select SORT.
9. Click the arrow of the Sort by box and select PRODUCT.
10. Click OK.
TOTALS AND SUBTOTALS
11. Click the DATA menu again and select
Subtotals…
12. Select PRODUCT in the At each change in:
box.
13. Select Sum in the Use Function: box.
14. Select AMOUNT in the Add Subtotal to: box.
15. Click OK.
16. Examine your data now.
USING CHARTS
• A chart is a pictorial representation of data.
• Charts make it easy for users to see
comparisons, patterns, and trends in data.
• For example, a chart can be used to check at a
glance whether sales are falling or rising over
a period of time.
TYPES OF CHARTS
• Different types of charts can be used in
Microsoft Excel.
• Examples of Microsoft Excel charts are:
• Column charts
• Bar charts
• Pie charts
• Line charts
CREATING A CHART
• To create a chart, you must first enter the data
for the chart on the worksheet.
• Then select that data and use the Chart
Wizard to guide you through the process of
choosing the chart type and the various chart
options.
• A chart is linked to the worksheet data it is
created from and is updated automatically
when the worksheet data changes.
COMPUTER NETWORKS
What is a computer network?
• A computer which is not connected to another
computer is called a stand-alone computer.
• Stand-alone computers have limited benefits.
• Computers are often links to one another to form
computer networks.
• A computer network is an interconnection of
computers.
• It is a link between two or more computers.
What are the reasons for
networking computers?
• To share data
– For example, a centralized database can be used
to store all the records of an organization.
– The same data in the database can be accessed by
everyone.
• To share tasks
– Co-workers can collaborate on tasks to speed up
processing.
What are the reasons for
networking computers?
(Continued)
• To share computer resources
– Expensive resources, such as hard disk drives,
printers and software programs can be shared.
– Sharing these resources greatly reduces
acquisition and maintenance costs.
• To make communication more efficient and
effective
– It is easier and cheaper for people to
communicate.
How can computers be linked?
• There are many ways in which computers can be
networked.
• The type of computer network formed is generally
determined by the distance which the network will
cover.
• On the basis of distance, there are three basic
computer networks:
– Local Area Network (LAN)
– Metropolitan Area Network (MAN)
– Wide Area Network (WAN)
How can computers be linked?
(Continued)
• A LAN is a computer network within a room, a
building or a small area such as a school campus.
• Computers in a LAN are separated by distances of up
to a few kilometers.
• A LAN enables the fast and effective transfer of
information within a group of users and reduces
operational costs.
• An example of a LAN is the TVTC computer network.
How can computers be linked?
(Continued)
• A MAN is a computer network within a town
or district.
• A MAN covers a longer distance than a LAN.
• An example of a MAN is the computer
network used to connect branches of a bank
within a town.
How can computers be linked?
(Continued)
• WANs connect computers separated by longer
distances, for example in different towns, in different
countries or different continents.
• WANs also use specialized and expensive hardware
and leased communications services.
• An example of a WAN is the Internet which
interconnects many computer networks in the world.
How can computers be linked in a
LAN?
(Continued)
• The way computers and other resources are
laid out is known as topology.
• There are various LAN topologies in use.
• Examples of LAN topologies are:
– Star topology
– Ring topology
– Bus topology
– Tree topology
– Mesh topology
STAR TOPOLOGY
• In this topology, there is a central computer
called the host or server to which all other
nodes are linked.
• The computers connected to the host are
called terminals or workstations or slaves or
clients.
STAR TOPOLOGY
Host
(Continued)
STAR TOPOLOGY
(Continued)
• A high speed computer, e.g. a minicomputer
or a mainframe computer, can be used as a
server.
• A star network is also commonly known as a
client-server network.
STAR TOPOLOGY
(Continued)
Advantages of star topology
• It is relatively cheaper because computer resources,
e.g. printers and software are concentrated on the
server.
• There is better or improved security and control for
data and other resources.
• It is cheaper to install and easier to implement.
• A faulty client does not affect network traffic
between other clients.
STAR TOPOLOGY
(Continued)
Disadvantages of star topology
• The whole network is affected when the
server is down.
• The whole network is affected if the server is
slow.
• Extra hardware is required in order to extend
the network beyond the limit of the star
network.
• Requires more cable length.
RING NETWORK
• There is no host and no slave; all the
computers are peers.
• Computers are connected to a cable that runs
round forming a ring.
Peer
Peer
Peer
Peer
RING NETWORK
(Continued)
• Because there is no host computer to control
communication, a special signal called a token
is sent round the network.
• The computer with the token is the one that is
able to send while the other computers can
receive only.
RING NETWORK
(Continued)
Advantages of ring topology
• This type of LAN is faster than the star
network.
• There are no signal collisions during
transmission.
• All stations have equal access.
• Because each station on the ring acts as a
repeater, ring networks can span longer
distances.
RING NETWORK
(Continued)
Disadvantages of ring topology
• There is poor security for data.
• It is the most expensive topology.
• Failure of one node may affect others.
• For these reasons, ring networks are no longer
popular.
BUS NETWORK
• In this network, a cable called a bus runs
through.
• All the computers in the network are linked to
this cable.
Bus
BUS NETWORK
(Continued)
• Sometimes computers may transmit signals at
the same time.
• Transmitted signals are broadcast.
• Every computer receives a transmitted signal
but checks if the signal is its own.
BUS NETWORK
(Continued)
Advantages of bus topology
• Theoretically, this is the fastest network.
• It is easier to connect a computer to the bus.
• It requires less cable length than star network.
BUS NETWORK
(Continued)
Disadvantages of bus topology
• There is a possibility of signal collisions.
• The entire network shuts down if there is a break in
the bus.
• The process of preventing signal collisions makes this
network slow and expensive practically.
• Requires terminators at the end of the bus.
• It is difficulty to identify the problem if the network
shuts down.
BUS NETWORK
(Continued)
How signal collisions are prevented
• A special technique known as carrier sense multiple
access/collision detection (CSMA/CD) is used.
• CSMA/CD works as follows:
– A computer wishing to transmit first listens in to check if
there is no signal on the network.
– If no signal is detected, the computer sends its signal and
listens in again to be sure that no other computer
transmitted at the same time.
BUS NETWORK
(Continued)
• How signal collisions are prevented (Continued)
– If another signal is detected, both computers
terminate transmission and wait a random length
of time.
– The procedure is repeated until each computer
sends its signal.
TREE TOPOLOGY
MESH TOPOLOGY
COMMUNICATIONS CHANNELS
• A communications channel is a link between
nodes on a network.
• It is a transport medium that conveys signals
from one network node to another.
• A communications channel can either be
wired or wireless.
• Communications channels differ from each
other mainly in the amount of data signals
which they can transmit at a time.
COMMUNICATIONS CHANNELS
(Continued)
• The capacity or size of a communications channel
is known as bandwidth.
• Bandwidth is the amount of information that can
be sent through a communications channel in a
given amount of time.
• A channel with a greater bandwidth carries more
signals, and therefore transmits data faster than a
channel with a lower bandwidth.
COMMUNICATIONS CHANNELS
(Continued)
• Bandwidth is measured by the number of bits
per second (bps) that can be sent over a
connection.
• For example, the bandwidth of a connection
can be quoted as 10Mbps, i.e. 10 megabits
per second.
COMMUNICATIONS CHANNELS
(Continued)
WIRED CHANNELS
• Wired channels form physical links.
• Examples are UTP, Coaxial cable and Optical
fibre.
UTP
• UTP stands for Unshielded Twisted Pair.
• UTP consists of a pair of copper wires twisted
around each other.
COMMUNICATIONS CHANNELS
UTP
(Continued)
COMMUNICATIONS CHANNELS
(Continued)
Advantages of UTP
• The cables are cheaper.
• UTP is easier to install.
• Modern UTP (e.g. Cat 6) has higher data transfer
rates or bandwidth.
Disadvantages of UTP
• Data transfer rates are low for old UTP.
• It has a distance limit of approximately 100m.
• There is more environmental signal interference.
COMMUNICATIONS CHANNELS
(Continued)
Coaxial cable
• A coaxial cable consists of a central copper
wire as one conductor surrounded by a mesh
of wire as outer conductor.
COMMUNICATIONS CHANNELS
• Coaxial cable
(Continued)
COMMUNICATIONS CHANNELS
(Continued)
Advantages of coaxial cable
• Coaxial cables transmit data faster than UTP
because their bandwidth is larger.
• Coaxial cables can cover longer distances than
UTP.
• There is less signal interference from the
environment.
COMMUNICATIONS CHANNELS
(Continued)
Disadvantages of coaxial cable
• They are more costly to produce and to install
than UTP.
• They are very bulky, i.e. large and heavy.
• They are not supported by some network
standards.
• For these reasons, coaxial cables are not very
commonly used in computer networks
nowadays.
COMMUNICATIONS CHANNELS
(Continued)
Fibre Optic
• This is a very thin rod of extremely pure glass
the size of a human hair.
• Signals are transmitted in form of light instead
of in form of an electric current.
• Each fibre is bent at a special angle to allow
for total-internal reflection of light.
COMMUNICATIONS CHANNELS
Fibre optic
(Continued)
COMMUNICATIONS CHANNELS
(Continued)
Advantages of fibre optic
• Fibre optic cables carry more data because they have
a much greater bandwidth than metal cables.
• Fibre optic cables are less susceptible than metal
cables to interference.
• Fibre optic cables are much thinner and lighter than
metal wires.
• Data can be transmitted digitally (the natural form
for computer data) rather than analogically.
COMMUNICATIONS CHANNELS
(Continued)
Disadvantages of fibre optic
• The main disadvantage of fiber optics is that the
cables are expensive to buy and install.
• In addition, they are more fragile than wire.
• The glass can be affected by various chemicals
including hydrogen sulphide gas.
• Most fibres become opaque when exposed to
radiation.
• Optical fibres cannot be joined together as easily as
copper cable and require additional training of
personnel to handle.
COMMUNICATIONS CHANNELS
(Continued)
WIRELESS CHANNELS
• Wireless channels allow for the sending of data as
electromagnetic waves.
• Examples are infrared, radio, Bluetooth,
microwaves, and satellite.
• The advantage of some of these channels is that data
can be sent over very long distances by remote.
• Remote means no physical connection between
sending and receiving nodes.
COMMUNICATIONS CHANNELS
(Continued)
• The picture below shows satellite dishes.
COMMUNICATIONS CHANNELS
(Continued)
• A satellite dish transmits and receives signals to and
from a satellite which is positioned in space above
the earth.
• Using satellite communication, messages can be sent
round the globe in just a fraction of a second.
• A common type of dish is the VSAT such as the one at
TVTC.
• VSAT stands for Very Small Aperture Terminal.
COMMUNICATIONS CHANNELS
• Bluetooth symbol
(Continued)
COMMUNICATIONS CHANNELS
• Example of Bluetooth network
(Continued)
OTHER NETWORK REQUIREMENTS
• Transport media are one of the three things
required in order to link computers together.
• The other two are protocols and a naming
system.
OTHER NETWORK REQUIREMENTS
(Continued)
• Protocols are a set of rules that govern the
way communication has to be established.
• A naming system or conversion controls how
machines are identified on the network.
OTHER NETWORK REQUIREMENTS
(Continued)
ETHERNET
• Ethernet has become the most common
transport technology.
• Ethernet enables computers to interconnect
on a local area network.
• Ethernet uses coaxial, twisted-pair or fibre
optic cables as a communication medium.
OTHER NETWORK REQUIREMENTS
(Continued)
TCP/IP
• The protocol that has become the standard is
the Transmission Control Protocol/Internet
Protocol.
• TCP/IP enables different types of computers
and networks on the Internet to communicate
with one another.
OTHER NETWORK REQUIREMENTS
(Continued)
TCP/IP
• TCP/IP consists of two sets of protocols.
• TCP defines how data is transferred across the
Internet to their destination.
• IP defines how data is divided into chunks, called
packets, for transmission; it also determines the path
each packet takes between computers.
• On a network each computer is assigned an address
called IP address so that signals can be delivered to
the correct destination.
OTHER NETWORK REQUIREMENTS
(Continued)
TCP/IP
• For example, 165.165.38.19 is the IP address
of Google.
DNS
• Hosts or nodes on a network are identified by
names derived from a naming conversion
called Domain Name System.
OTHER NETWORK REQUIREMENTS
(Continued)
DNS
• Because IP addresses are difficult to
remember by heart, a naming system was
introduced to simplify the task.
• Each IP address is assigned a domain name.
• A DNS server translates names into IP
addresses.
OTHER NETWORK REQUIREMENTS
(Continued)
DNS
• When a user enters a domain name e.g.
www.google.com, into the web browser, the
local DNS server tries to translate it to an IP
address by consulting its database.
OTHER NETWORK REQUIREMENTS
(Continued)
DNS
• If it cannot find the address then the local
DNS server consults other DNS servers on
the Internet.
• If the domain name cannot be resolved by
all the DNS servers, the Web browser
displays an error message such as The
webpage cannot be found.
OTHER NETWORK REQUIREMENTS
(Continued)
DNS
• The IP address naming system uses a name
system that has names in levels.
• Examples of the top-level domain, also known
as the primary domain, are names that end
with .com, .edu, .org, .gov, e.t.c.
• .com means commercial organisation.
• .edu means education organisation.
OTHER NETWORK REQUIREMENTS
(Continued)
DNS
• The top-level domain may also define the
country in which the DNS server is located,
e.g. .zm (Zambia), .uk (United Kingdom), .za
(South Africa).
• All computers on the Internet are required to
register to one of these primary domain
names.
OTHER NETWORK REQUIREMENTS
(Continued)
DNS
• For example, a domain name such as
business_studies.tvtc.edu.zm is interpreted as
follows:
– zm defines the country Zambia.
– edu shows that the network belongs to an
educational institution.
– tvtc gives the name of that educational
institution.
– business_studies gives the name of the sub
network within tvtc.
SETTING UP AN ETHERNET LAN
• To set up a LAN you need the following
resources.
– A hub or a switch
– Communications channel, e.g. wired or wireless
– Communications software
– A network interface card (NIC)
SETTING UP AN ETHERNET LAN
(Continued)
• Hub or switch is used to interconnect computers and
other network resources or segments.
• Hub or switch is also required to direct signals to
their destinations on the LAN.
• Communications channel is required as a passage of
signals between network devices.
• Communications software is required for controlling
the hardware and the transmission of signals.
• A network interface card is required for connecting
network devices onto the LAN.
SETTING UP AN ETHERNET LAN
(Continued)
• A hub differs from a switch in certain respects.
• A switch is more “intelligent” than a hub.
• When a hub receives data meant for one device, it
broadcasts the signal to all the devices on the
network.
• Unlike a hub, a switch first identifies the owner of
the data and then sends only to that destination.
• A switch also works faster than a hub.
EXAMPLE OF AN ETHERNET LAN
.
SWITCH
SWITCH
HUB
THE INTERNET
• Internet is an interconnection of computer
networks.
• Internet is rated one of the most significant
human inventions of all time.
• The Internet offers many possibilities for
individuals and organizations.
THE INTERNET
(Continued)
There are three main functions of the Internet:
1. Communication
• One can contact and exchange information
with friends and organisations anywhere in
the world.
2. Retrieval of information
• One can have access to a broad range of data
and information from other computers
around the globe.
3. Commerce
• One can advertise, buy and sell goods and
services on the Internet.
CONNECTING A LAN TO THE
INTERNET
• To connect a LAN to the Internet you need the
following resources:
– Router
– Internet software
– Internet service provider (ISP)
– Communications channel (wired or wireless)
CONNECTING A LAN TO THE
INTERNET
(Continued)
• The router is required for two reasons:
– To split the signal into packets for effective
transmission.
– To identify the most convenient route for each
packet to take to its destination.
• Internet software is required for controlling
the hardware and for correcting errors during
transmission.
• An ISP provides advanced and expensive
resources for accessing the Internet.
ROUTER
MODEM and NIC
• Modem stands for Modulator Demodulator.
• A modem is a device that connects the computer to
the telephone line.
• In a computer data signals travel in parallel lines, but
in a telephone wire the signals travel serially, i.e. one
behind the other.
• We say that computers handle data in digital form
and telephone wires transmit data in analog form.
• A modem is used to convert data from digital to
analog, and from analog to digital.
MODEM and NIC
(Continued)
MODEM and NIC
(Continued)
MODEM and NIC
(Continued)
• NIC stands for Network Interface Card.
• A NIC connects a computer to a LAN, not to a
telephone wire.
• A NIC also does the conversion of signals from
digital to analog and vice versa.
• Generally, a NIC transmits signals faster than a
modem.
• A NIC has a unique number which identifies
every computer on a network.
MODEM and NIC
NIC
(Continued)
BROWSING THE INTERNET
• To browse the Internet is simple.
• You simply start the Internet browser
software.
• If you already know the URL, i.e. the address
of what you want, you simply type it in the
address box in the browser and then click on a
button to get to the destination.
BROWSING THE INTERNET
(Continued)
• URL stands for Uniform Resource Locator.
• An example of a URL is
http://www.yahoo.com
• Web browser is a software program that
connects your computer to the Internet.
• Examples of web browsers are Internet
Explorer, Mozilla FireFox and Opera.
• The best way to browse the Internet is to use
an Internet Search Engine.
BROWSING THE INTERNET
(Continued)
• A Search Engine is a software program in which the
user types keywords instead of the URL.
• Examples of search engines are Google and Yahoo.
• The Search Engine uses the keywords to locate
information in servers on the Internet.
• It lists down links to websites or web pages where
the actual details are found.
BROWSING THE INTERNET
(Continued)
• The web pages are listed in the order of the
number of visits made to that page.
• Pages that are visited more frequently are
listed at the top.
• An example of a list of links given by a search
engine after entering the keywords Search
Engine is shown below.
BROWSING THE INTERNET
(Continued)
• Web search engine - Wikipedia, the free encyclopedia
A web search engine is designed to search for information on
the World Wide Web and FTP servers. The search results are
generally presented in a list of ...
History - How web search engines work - See also - References
• AltaVista
AltaVista provides the most comprehensive search experience
on the Web! ... SEARCH: Worldwide or Select a country
RESULTS
BROWSING THE INTERNET
(Continued)
• To read the article, you click on the link.
• The links are shown as underlined texts, and
most of them are in blue.
• You can narrow your search by using
Advanced Search.
• After you click on the Advanced Search link,
you enter your preferences in a form.
BROWSING THE INTERNET
(Continued)
• The Internet is a global infrastructure of
computer networks.
• The Internet is used to access information
which is stored in the World Wide Web
(WWW).
• The World Wide Web is an infrastructure of
information.
BROWSING THE INTERNET
(Continued)
• Websites consist of Web pages.
• The information in the WWW is found in
Websites.
• Actually, websites are servers with huge
databases.
• A web page is a place within the website
where documents are located.
BROWSING THE INTERNET
(Continued)
• The URL
http://homepages.uel.ac.uk/u0311625/topolo
gy.html, is the web page of a document.
• The website or server name is
homepages.uel.ac.uk
• The document name on the web page is
topology, and is in hypertext markup language
(html) format.
ELECTRONIC MAIL (E-MAIL)
• This is a facility available when one connects
to the Internet.
• One can send and receive text and both video
and audio messages using e-mail.
• To send e-mail, one types the message,
indicates the address to receive and clicks a
button.
ELECTRONIC MAIL (E-MAIL)
(Continued)
• E-mail is meant to make mail more efficient.
• It also solves the problem of so much paper
wastage, unattended to telephones and delays
associated with traditional mail.
• It is also extremely cheap to send messages by
e-mail.
• The same message can be sent to many
people at the same time.
ELECTRONIC MAIL (E-MAIL)
(Continued)
• To create an email address, you do the
following:
– Start the browser software, e.g. Internet Explorer.
– Click on the mail client, e.g. Gmail in google.
– Click on Create an Account.
– Complete the form which appears and select
submit at the end of the form.
UNDERSTANDING EMAIL ADDRESSES
• Normally an email address consists of three
parts.
• These parts are:
– Username
– Server name
– Top-level domain, i.e. primary domain name.
• The username is separated from the rest by
the @ symbol.
UNDERSTANDING EMAIL ADDRESSES
(Continued)
• For example, in the address
mstembo@tvtc.edu.zm, the username is
mstembo, the host computer name is tvtc,
and the primary domain name is edu in the
country Zambia.
• Note that the name that follows the @ symbol
immediately is always the host computer
name, i.e. the server name.
INTRANET
• The Internet consists of many networks.
IT SECURITY
• Security refers to the defence necessary to ward off
threats imposed on IT resources.
• Security is ensuring that resources are free from
unauthorised internal and external manipulation.
• There are two types of security: physical security
and data security.
• Data security ensures that data, information and
software are safe from internal and external threats.
• Physical security ensures that all the various types of
hardware are safe.
TYPES OF THREATS
Some of the threats are as follows:
–
–
–
–
–
–
–
Unauthorised access of individuals to data storage.
Incorrect use of hardware and software, media or
computer rooms.
Unauthorised manipulation of data files or equipment.
Theft of data or hardware.
Fire/water.
Environmental conditions, e.g. temperature and
humidity.
Viruses and other malicious code.
MEASURES TO IMPROVE ON
SECURITY
• Examples of possible measures are:
• Keeping all doors to computer rooms locked
so that access is upon permission granted.
• Locking computers so that only personnel with
computer keys can unlock and use them.
• Using passwords to start computers and to
open files.
MEASURES TO IMPROVE ON
SECURITY
(Continued)
• Installing alarm systems so that the presence
of intruders, fire, smoke, water etc, can be
identified.
• Installing air conditioners so that the room
temperature and humidity are automatically
regulated
MEASURES TO IMPROVE ON
SECURITY
(Continued)
• Backing up all data and programs so that
should the data and programs that are used
become corrupt, backups can quickly be used.
• Keeping data and program backups in a
separate room which is also secured.
• Installing antivirus software and keeping it
updated.
MEASURES TO IMPROVE ON
SECURITY
(Continued)
• Installing Firewalls to scrutinize all signals that
enter or leave the computer or the network.
• Training users about how to be security
conscious and how to react in an event of a
disaster.
• Training users how to properly use software
and hardware.
COMPUTER VIRUSES
• A computer virus is a program that is meant to
cause some kind of damage or discomfort
when it is activated on an infected computer.
• Virus is a general term, but viruses are in
categories.
COMPUTER VIRUSES
(Continued)
• Viruses are those malicious codes that are capable of
replicating themselves and attack computer
programs in memory.
• A Trojan horse is a program disguised as something
useful, which when run does damage to the
computer system while appearing to do something
else.
• A virus that propagates itself across computer
networks, usually via e-mail, is referred to as a
worm.
• The increase in transactions over the Internet has
greatly increased the chance of virus infection.
HOW COMPUTERS BECOME INFECTED
WITH VIRUSES
• There are many ways in which a computer may
become infected by a virus.
• Some of the common ones are as follows:
– Transfer of removable storage media, e.g. floppies,
CDs and flash disks, from one computer to another.
– Through e-mail; when you receive and open an
infected e-mail, your computer gets infected.
– Through downloads, e.g. of music, pictures, videos,
documents and software on the Internet.
HOW TO MINIMISE VIRUS ATTACKS
To minimise the possibility of your computer
getting infected by viruses, observe the
following guidelines:
• Avoid exchanging removable storage media
with other people.
• Don’t read e-mail from people you do not
know.
• Don’t read e-mail from people you know but
from whom you do not expect e-mail.
HOW TO MINIMISE VIRUS ATTACKS
(Continued)
• Avoid the temptation to download anything
you find interesting on the Internet.
• Don’t click on pop ups and other adverts that
flash on your screen as you browse the
Internet.
• Search for information by typing keywords in
the Search Engine.
HOW TO MINIMISE VIRUS ATTACKS
• Ensure that your computer has latest versions
of antivirus software.
• Always update the antivirus software from the
Internet.
• Always scan your computer for viruses.
HACKERS AND CRACKERS
• A hacker is a person who gains remote access
to a computer or network not necessarily for
bad motives.
• A cracker is a person who also gains remote
access to someone’s computer or network but
with the intension to cause havoc.
HACKERS AND CRACKERS
(Continued)
• To protect yourself against hackers, you should use
very secure passwords and encrypt your data
during transmission.
• Secure passwords are those that do not use any
names of people, organisations and things like
dates which a cracker can easily decode.
• Secure passwords should contain alphanumeric
characters that should be extremely difficult to
guess by anyone, and should be long.
HACKERS AND CRACKERS
(Continued)
• Hackers and crackers use very sophisticated methods
to crack passwords.
• They use advanced programs which are capable of
unlocking what you may think is very secure.
• One approach to defeat them is to ensure that you
don’t use the same password for a long time.
• However, should you forget the password you will
not be allowed access to your own data or computer
system.