INTRODUCTION TO

INFORMATION
TECHNOLOGY AND
COMPUTING

SCS 1101

Lecture 1

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Course Objectives

■ To expose the student to a computer, its characteristics and functions

■ To introduce the student to the window environment and
directories/files
■ To expose the student to the notions of software and hardware
■ To help the student appreciate the use of computers in solving many
societal problem

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 ICT
ICT is an acronym of Information and Communication Technologies. The
set of technologies developed to manage information and send it
from one place to another.
This implies that ICT concerns all modern gadgets that are coming to
market every other day such as iPads, iPods, tablets, netbooks, mobiles,
smartphones etc apart from television and computers. C in ICT is
important and refers to communications of data over distance through
electronic means.

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COMPUTERS
A computer is an electronic device that takes input such as
numbers, text, sound, image, animations, video, etc., processes it, and
converts it into meaningful information that could be understood,
presenting the changed input (processed input) as output.
Or a computer is an electronic machine/device which can input
data, process them according to the instruction given and then give out
the meaningful information

■ Information: Knowledge that is communicated.

■ Data: Facts and figures which relay something specific, but are not
organized in any way and which provide no further information
regarding patterns, context, etc. So data means "unstructured facts
and figures that have the least impact on the typical manager."
■ Note: the term ‘raw data’ refers to unprocessed information 4
Advantages of Computers
High Speed
 Computer is a very fast device.
 It is capable of performing calculation of very large amount of data.
 The computer has units of speed in microsecond, nanosecond, and even the
picosecond.
 It can perform millions of calculations in a few seconds as compared to man
who will spend many months to perform the same task.

Accuracy
 In addition to being very fast, computers are very accurate.

 The calculations are 100% error free.

 Computers perform all jobs with 100% accuracy provided that the input is
correct.

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Storage Capability
 Memory is a very important characteristic of computers.
 A computer has much more storage capacity than human beings.
 It can store large amount of data.
 It can store any type of data such as images, videos, text, audio, etc.

Diligence
 Unlike human beings, a computer is free from monotony, tiredness, and lack of
concentration.
 It can work continuously without any error and boredom.
 It can perform repeated tasks with the same speed and accuracy.

Versatility
 A computer is a very versatile machine.
 A computer is very flexible in performing the jobs to be done.
 This machine can be used to solve the problems related to various fields.
 At one instance, it may be solving a complex scientific problem and the very next
moment it may be playing a card game.

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Reliability
 A computer is a reliable machine.
 Modern electronic components have long lives.
 Computers are designed to make maintenance easy.

Automation
 Computer is an automatic machine.
 Automation is the ability to perform a given task automatically. Once the computer receives
a program i.e., the program is stored in the computer memory, then the program and
instruction can control the program execution without human interaction.

Advantages of using computers

Reduction in Paper Work and Cost
 The use of computers for data processing in an organization leads to reduction in paper
work and results in speeding up the process.
 As data in electronic files can be retrieved as and when required, the problem of
maintenance of large number of paper files gets reduced.
 Though the initial investment for installing a computer is high, it substantially reduces the
cost of each of its transaction.
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 Disadvantages of computers
No I.Q.
 A computer is a machine that has no intelligence to perform any task.
 Each instruction has to be given to the computer.
 A computer cannot take any decision on its own.

Dependency
 It functions as per the user’s instruction, thus it is fully dependent on humans.

Dis Advantages of using computers

Environment
 The operating environment of the computer should be dust free and suitable.
.

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Components of a computer

The basic components of a modern digital computer are:

■ Input Device
■ Output Device
■ Central Processor Unit (CPU)
■ Mass storage device and memory

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 Input and output devices

The computer will be of no use unless it is able to communicate with the

outside world. Input/Output devices are required for users to
communicate with the computer.
In simple terms, input devices bring information INTO the computer and
output devices bring information OUT of a computer system.
These input/output devices are also known as peripherals since they
surround the CPU and memory of a computer system.

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 Input device
Data and instructions must enter the computer system before any
computation can be performed on the supplied data. The input unit that
links the external environment with the computer system performs this
task.
Data and instructions enter input units in forms that depend upon
the particular device used. For example, data is entered from a keyboard
in a manner similar to typing, and this differs from the way in which data
is entered through a mouse, which is another type of input device

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 Input device
In short, an input unit performs the following functions.
■ It accepts (or reads) the list of instructions and data from the outside
world.
■ It converts these instructions and data in computer acceptable
format.
■ It supplies the converted instructions and data to the computer
system for further processing

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Examples of input devices

 Graphics Tablets  Keyboard

 Cameras  Microphone
 Trackballs  Mouse (pointing device)
 Barcode reader  Scanner
 Digital camera  Webcam
 Gamepad  Touchpads
 Electronic Whiteboard  Pen Input

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Input Devices
■ Keyboard
It is a text base input device that allows the user to input alphabets,
numbers and other characters. It consists of a set of keys mounted on
a board. The layout of the keyboard is like that of traditional
typewriter, although there are some additional keys provided for
performing additional functions. Keyboards are of two sizes 84 keys or
101/102 keys, but now keyboards with 104 keys or 108 keys are also
available for Windows and Internet.
Alphanumeric
Keypad / Special Function Keys
function Keys Cursor
Movement
Keys

Numeric
Keypad
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No. Keys Description
1 Alphanumeric It consists of keys for English alphabets (A to Z), 0 to
Keypad 9 numbers, and special characters like +,−, /, *, ( , )
etc.
2 Function Keys There are twelve function keys labelled F1, F2, F3…
F12. The functions assigned to these keys differ from
one software package to another. These keys are also
user programmable keys.
3 Special- These keys have special functions assigned to them
function Keys and can be used only for those specific purposes.
Functions of some of the important keys are defined
•Enter below.
- It is similar to the ‘return’ key of the typewriter and
•Spacebar is used to execute a command or program.
•Backspace - It is used to enter a space at the current cursor
location.
•Delete - This key is used to move the cursor one position to
•Insert the left and also delete the character in that position.
-It is used to delete the character at the cursor
•Shift position.
-Insert key is used to toggle between insert and
overwrite mode during data entry.
-This key is used to type capital letters when pressed
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•Caps Lock along with an alphabet key. Also used to type the
special characters located on the upper-side of a key
that has two characters defined on the same key.
-
No. Keys Description
3 •Tab - Tab is used to move the cursor to the next tab
position defined in the document. Also, it is used to
insert indentation into a document.
•Ctrl -Control key is used in conjunction with other keys
to provide additional functionality on the keyboard.
•Alt - Also like the control key, Alt key is always used in
combination with other keys to perform specific
•Esc tasks.
- This key is usually used to negate a command.
Also used to cancel or abort executing programs.
4 Numeric Numeric keypad is located on the right side of
Keypad the keyboard and consists of keys having
numbers (0 to 9) and mathematical operators
(+ − * /) defined on them. This keypad is
provided to support quick entry for numeric
data.
5 Cursor These are arrow keys and are used to move
Movement Keys the cursor in the direction indicated by the
arrow (up, down, left, right). 16
■ Mouse
The mouse is a small device used to point to a particular place on the screen and select in order to
perform one or more actions. It can be used to select menu commands, size windows, start
programs etc. The most conventional kind of mouse has two buttons on top: the left one being
used most frequently,
Mouse Actions
Left Click : Used to select an item.
Double Click : Used to start a program or open a file.
Right Click : Usually used to display a set of commands.
Drag and Drop : It allows you to select and move an item from one location to another. To achieve
this place the cursor over an item on the screen, click the left mouse button and while holding
the button down move the cursor to where you want to place the item, and then release it.

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■ Scanner
Scanner is an input device used for
direct data entry from the source
document into the computer
system. It converts the document
image into digital form so that it
can be fed into the computer.
Capturing information like this
reduces the possibility of errors
typically experienced during large
data entry.

Hand-held scanners are commonly seen in big stores to scan codes and
price information for each of the items. They are also termed the bar
code readers.

■ Bar code Readers

A bar code is a set of lines of
different thicknesses that represent
a number. Bar Code Readers are
used to input data from bar codes.
Most products in shops have bar
codes on them. Bar code readers
work by shining a beam of light on
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the lines that make up the bar code
and detecting the amount of light
that is reflected back.
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 Output Unit
The job of an output unit is just the reverse of that of an input unit. It
supplied information and results of computation to the outside world. Thus
it links the computer with the external environment.
As computers work with binary code, the results produced are also in the
binary form. Hence, before supplying the results to the outside world, it
must be converted to human acceptable (readable) form. This task is
accomplished by units called output interfaces
In short, the following functions are performed by an output unit.
■ It accepts the results produced by the computer which are in coded form
and hence cannot be easily understood by us.
■ It converts these coded results to human acceptable (readable) form.
■ It supplied the converted results to the outside world.

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Examples of output devices
■ Monitor (LED, LCD, CRT etc)
■ Printers (all types)
■ Plotters
■ Projector
■ Speaker(s)
■ Head Phone
■ Film Recorder

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MONITORS
■ It is a most common peripheral in computer is graphic display device.
■ Increasing demand for display of graphics, diagrams and pictures to
make visual presentation of information more effectively.
■ Easy user interaction and decision making.
■ A monitor or display (also called screen or visual display unit) is an
electronic visual display for computers.
MONITORS

■ Graphic display is made up of a series of serial dots(picture elements)

called “pixels” whose pattern produces images.
■ Main categories of display screen:
– Cathode Ray Tube (CRT)
– Liquid Crystal Display (LCD)
– Light Emitting Diode (LED)
– Plasma Display
MONITOR QUALITY AND
RESOLUTION
Quality:
■ Manufacturers describe quality by dot pitch.
■ Smaller dot pitches mean pixels are closely spaced which will yield a
sharper image.
■ Most monitors have dot pitches that range from 0.22mm to 0.39mm.
Resolution:
■ Indicates how densely packed the pixels are.
■ Most modern monitors can display 1024x768 pixels.
■ High end models can display 1280x1024
Cathode-Ray Tube (CRT)
Monitor
■ The CRT display is made up of small picture
elements called pixels. The smaller the pixels, the
better the image clarity or resolution. It takes more
than one illuminated pixel to form a whole
character, such as the letter ‘e’ in the word help.
■ A finite number of characters can be displayed on a
screen at once. The screen can be divided into a
series of character boxes - fixed location on the
screen where a standard character can be placed.
Most screens are capable of displaying 80
characters of data horizontally and 25 lines
vertically.

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BASIC CATHODE RAY TUBE
■ Electrons fired from the back
■ Phosphor is arranged in dots called pixels
■ Electron strikes the phosphor on screen
■ Electrons excite phosphor to glow
■ Exact phosphor will be lit up by deviating electron using deflection
plates.
FYI, PHOSPHORE

■ is a semi-conductor material which emits visible radiation in response

to the impact of electrons. (i.e. when it absorbs energy from some
source such as an electron beam, it releases a portion of this energy
in the form of light).
■ In response to a sudden change in the electron beam(from on to off),
the light emission does not fall instantaneously, there is a gradual
reduction challed ‘fluorescence’.
■ Flat-Panel Display Monitor
The flat-panel display refers to a class of video devices that have reduced
volume, weight and power requirement in comparison to the CRT. You
can hang them on walls or wear them on your wrists. Current uses of
flat-panel displays include calculators, video games, monitors, laptop
computer, and graphics display.

The flat-panel display is divided into two categories:

– Emissive Displays - Emissive displays are devices that convert
electrical energy into light. For example, plasma panel and LED
(Light-Emitting Diodes).
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– Non-Emissive Displays - Non-emissive displays use optical
effects to convert sunlight or light from some other source into
graphics patterns. For example, LCD (Liquid-Crystal Device).
 LIQUID CRYSTAL DISPLAY (LCD)
■ Light is projected from the back by
lighting system on a layer of liquid
crystal. Compact Cathod Fluorescent
Lamp (CCFL) is used as light source.
■ Unpolarized light passes through rear
glass following polarizing film. Polarizer
helps to strikes the exact crystal.
Crystal modulated light passed
through color filter and then through
another polarizer to produce colored
image to user.
■ This image is then displayed on the
screen
ADVANTAGES OF LCD

■ The liquid crystal has a unique advantage of having low power

consumption than the LED or cathode ray tube.
■ Technology can be used in varieties of display devices: TV, Video
Cameras, Smartphones, Thermometers etc.
■ Provides excellent contrast
■ LCD’s are thinner and lighter when compared to cathode ray tube
■ Normal Life span : 10,000 - 50, 000 hours
DISADVANTAGES OF LCD

■ After a while the LCD display the some of the pixels will die(dead
pixels) and you may see a discoloured spot on a black spot on the
display.
■ The cost of a LCD is considerably at a high price.
■ The LCD display will have slow response times.
■ The LCD display has a fixed resolution display and cannot be changed.
■ The viewing angle of a LCD display is very limited.
LIGHT EMITTING DIODES(LEDS)

■ Emissive display technology which is like an LCD screen, but instead

of having a normal CCFL backlight, it uses light-emitting diodes (LEDs)
as a source of light behind the screen.
– Some available in market uses same liquid crystal to form pixels
with LED as backlight.
– Some didn't have an LCD panel but instead have 3 small colored
LEDs per pixel with backlight.
■ An LED is more energy efficient and a lot smaller than a CCFL,
enabling a thinner television screen.
ADVANTAGES OF LED

■ Improved viewing angle than LCDs.

■ Thin screen with sleek design which is adjustable at any place.
■ LEDs are far better than LCD monitors because they do not use
fluorescent bulbs due to which they are lighter and thinner in weight.
■ LEDs consume less energy and save a lot of power.
■ LEDs provide bright image quality by enhancing the contrast and
enriching the range of colors.
ADVANTAGES OF LED

■ These LEDs monitor produces flicker free image which reduces eye
fatigue, eye strains and headaches.
■ They have a long lifespan in comparison to the LCD’s.
■ LEDs don’t produce heat because they do not contain the fluorescent
bulbs which can also cause damage by short-circuiting.
■ Life span : Around 100,000 hours
DISADVANTAGES OF LED

■ Top most disadvantage is the price rate at which they are available in
the market, which is very expensive.
■ LED performance largely depends on the ambient temperature of the
operating environment. Over-driving the LED in high ambient
temperatures may result in overheating of the LED package,
eventually leading to device failure.
■ LEDs must be supplied with the correct voltage and current at a
constant flow. This requires some electronics expertise to design the
electronic drivers.
 PLASMA MONITORS
■ Plasma Display Panel(PDP) is a type of flat panel
display now commonly used for large TV
displays(above 37-inch or 940 mm).
■ Many tiny cells located between two panels of
glass hold an mixture of noble gases as picture
element..
– non-flammable,inert gases,neon and xenon,
both of which are used in fluorescent lighting.
These gases are not harmful, either
individually or when combined.
■ The gas in the cells is electrically turned into
plasma which then excites phosphors to emit light
which user see as image
ADVANTAGES OF PLASMA

■ Plasma TVs allows richer colors in a wider range i.e.chromatic range of

plasma screens is much broader than for CRT and LED displays.
■ The viewing angles are very wide, especially compared to LCD
displays. The main reason is that the light is generated in the pixels
themselves, unlike LCD technology.
■ Plasma screens need no polarizer.
■ Plasma displays can have very large diagonal measurements (32 to
50 inches) with minimal thickness.
DISADVANTAGES OF PLASMA

■ Since a plasma pixel needs an electricity to emit light, a pixel is either

lit or unlit, but has no intermediate state. So more expensive to
control brightness.
■ May causes visual discomfort eye (i.e. fatigue without the viewer even
being aware of it) at close distances.
■ Finally there's the economic factor: plasma displays are expensive as
plasma panel's control mechanism require specific high performance
semiconductors.
■ Printers
Printers are used to produce paper (commonly known as
hardcopy) output. Based on the technology used, they can be
classified as Impact or Non-impact printers.
Impact printers use the typewriting printing mechanism wherein
a hammer strikes the paper through a ribbon in order to
produce output. Dot-matrix and Character printers fall under
this category.
Non-impact printers do not touch the paper while printing. They
use chemical, heat or electrical signals to etch the symbols on
paper. Inkjet, Deskjet, Laser, Thermal printers fall under this
category of printers.
When we talk about printers we refer to two basic qualities
associated with printers: resolution, and speed. Print
resolution is measured in terms of number of dots per inch
(dpi). Print speed is measured in terms of number of
characters printed in a unit of time and is represented as
characters-per-second (cps), lines-per-minute (lpm), or pages-
per-minute (ppm).

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■ Plotter:
Plotters are used to print graphical output on paper. It interprets
computer commands and makes line drawings on paper using
multicoloured automated pens. It is capable of producing graphs,
drawings, charts, maps etc.
Computer Aided Engineering (CAE) applications like CAD (Computer
Aided Design) and CAM (Computer Aided Manufacturing) are typical
usage areas for plotters.

■ Audio Output: Sound Cards and Speakers:

The Audio output is the ability of the computer to output sound. Two 40

components are needed: Sound card – Plays contents of digitized

recordings, Speakers – Attached to sound card.
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Central processing unit (CPU)
The main unit inside the computer is the CPU. This unit is
responsible for all events inside the computer. It controls all internal and
external devices
Similarly, in a computer system, all major calculations and
comparisons are made inside the CPU and the CPU is also responsible for
activating and controlling the operations of other units of a computer
system
The control Unit and the Arithmetic and Logic unit of a computer
system are jointly known as the Central Processing Unit (CPU). The CPU is
the brain of any computer system. In a human body, all major decisions
are taken by the brain and the other parts of the body function as
directed by the brain.

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 Central processing unit (CPU)

The arithmetic and logic unit (ALU) of a computer system is the

place where the actual execution of the instructions take place during the
processing operations. All calculations are performed and all comparisons
(decisions) are made in the ALU

The control unit (CU) is a component of a computer's central

processing unit (CPU) that directs the operation of the processor. It tells the
computer's memory, arithmetic and logic unit and input and output devices
how to respond to the instructions that have been sent to the processor

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Storage Unit/ memory
The data and instructions that are entered into the computer
system through input units have to be stored inside the computer before
the actual processing starts. Similarly, the results produced by the
computer after processing must also be kept somewhere inside the
computer system before being passed on to the output units.
Moreover, the intermediate results produced by the computer
must also be preserved for ongoing processing. The Storage Unit or the
primary / main storage of a computer system is designed to do all
these things. It provides space for
■ storing data and instructions,
■ space for intermediate results and also
■ space for the final results

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Computer hardware
Hardware is best described as a device that is physically
connected to the computer or something that can be physically
touched. Hardware and software interact with one another: software
tells hardware which tasks it needs to perform.
Examples of computer hardware include:-

Other types of
hardware include:-
 Motherboard
 RAM
 Hard Drive

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Classification of hardware
Hardware devices can be classified into four distinct categories:
■ Input devices: For raw data input.
■ Processing devices: To process raw data instructions into information.

■ Output devices: To disseminate data and information.

■ Storage devices: For data and information retention

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 Peripherals
A computer peripheral, or peripheral device, is an external
object that provides input and output for the computer.
Some common input devices include: Keyboard, mouse,
Touchscreen, pen tablet, Joystick, scanner, digital camera video camera,
microphone etc.
Some common output devices include: monitor, projector, TV
screen, printer, plotter, speakers etc

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 Social and economic implications of
the use of computers

■ Changing employment
Human skills are being challenged by computers hence the need to re
skill
■ Computerizing existing jobs
Computers have relieved many tedious, repetitive tasks requiring a
higher level of concentration and accuracy
■ Off shore outsourcing
Computer technology has enabled jobs to be relocated anywhere in the
world especially with technologies like skyping and teleconferencing

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■ Health and safety
Computers have greatly impacted the health sector through technologies
like ultrasounds, x rays, in the surgical section among others. This has
enabled to better manage health factors and in best scenarios avoid
others from occurring at all.
■ Privacy and integrity of data
One of the greatest benefits of using computers is that large quantities of
stored data are easily accessible both locally and over the networks
As the use of computers has become more wide spread keeping data
private has become increasingly important.
This can also be referred to other types of security like alerts and alarms
on physical buildings
■ Security and reliability of data
Maintain the privacy and integrity of data together with protecting data
against loss when failure of a storage device occurs, stolen or destroyed
by natural disaster or data maliciously deleted
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THE END

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