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Introduction to
Computers

INTRODUCTION TO COMPUTERS
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A computer automatically accepts data & instructions as input from an Input device, stores them
temporarily in its memory, then processes that data according to the instructions given, and
finally transfers the processed data (Information) to an Output device
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- A computer has an internal memory, which stores data & instructions temporarily
awaiting processing, and even holds the intermediate result (information) before it is
communicated to the recipients through the Output devices
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The data is normally
held within the computer as it is being processed
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 A set of related instructions which specify how the data is to be processed
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Data:
Data is a collection of raw facts, figures or instructions that do not have much meaning to the
user
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TYPES OF DATA
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Digital (discrete) data:
Digital data is discrete in nature
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- Digital data is obtained by counting
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g
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Analogue (continuous) data:
Analogue data is continuous in nature
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Analogue data is obtained by measurement
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g
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Data Processing:
 It is the process of collecting all items of data together & converting them into information
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Introduction to
Computers

Information:
Information is the data which has been refined, summarized & manipulated in the way you want
it, or into a more meaningful form for decision-making
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Comparison between Data and Information
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Unprocessed (raw) facts or figures
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Not arranged
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Does not have much meaning to the user
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Cannot be used for decision-making
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It is the end-product of data processing
(processed data)
2
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3
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4
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Characteristics / Features of a Computer
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Speed
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They can perform a much complicated task much faster than a human being
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Accuracy:
Unlike human beings, computers are very accurate, i
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, they never make mistakes
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However, when an error
occurs the computer has a number of in-built, self-checking features in their electronic
components that can detect & correct such errors
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This means that, if you enter incorrect data into the computer and have it processed, the
computer will give you misleading information
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Reliability
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Therefore, if you want to add two numbers, but by mistake, give the computer a “Multiply”
instruction, the computer will not know that you intended to “ADD”; it will multiply the
numbers supplied
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Consistency:
Computers are usually consistent
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5
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A computer can store data & instructions for later use, and it can produce/ retrieve this data
when required so that the user can make use of it
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6
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Even if it has to do a million calculations, it will do the last one with the same speed and
accuracy as the first one
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Automation:
A computer is an automatic device
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It can also perform a variety of jobs as long as there is a well-defined procedure
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Versatile:
A computer can be used in different places to perform a large number of different jobs
depending on the instructions fed to it
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Imposition of a formal approach to working methods:
Because a computer can only work with a strict set of instructions, it identifies and imposes
rigid rules for dealing with the data it is given to process

PARTS OF A COMPUTER
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A Computer consists of the following parts/devices: 1
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2
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3
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4
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System Unit
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The components in the System unit include:  Central Processing Unit (CPU), which is also referred to as Processor
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 Power supply unit
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 Disk drives, which are used to store, record and read data
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They are designed to be placed on the floor
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b) Desktop system units
Desktop units lie on the desk with the monitor resting on top of the system unit
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It houses the CPU
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It has the computer’s Power switch
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Input devices
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• They accept data for processing & convert it into a suitable form that the computer can
understand
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The Keyboard
The keyboard looks like a typewriter, and has letters, numbers and other keys through which data
is entered into the computer
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The Mouse
It is a pointing device that enables the user to issue instructions to the computer by controlling a
special mouse pointer displayed on the screen
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Output devices are used to give the end results of data that was entered into the computer
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They accept data from processing devices & convert it into human sensible form
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When you type a letter or number on the
keyboard, it shows up on the monitor
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The monitor enables the user to monitor/track or see what is going on in the computer
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Memory storage devices
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• They hold data & programs until they are needed for processing
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Computer storage is divided into 2:
i)
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This is the storage found within the computer itself
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Examples: Random Access Memory (RAM) & Read Only Memory (ROM)
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Secondary (Backing) storage
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It is also used by the computer to supplement the computer’s main memory/
internal memory in case of mass storage purposes
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They allow large
quantities of information to be stored permanently on some form of magnetic media such
Magnetic tapes or disks
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Examples of secondary storage devices:
• Hard disk
• Cassette tapes
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* Magnetic Tapes
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* Zip disks
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Computer peripherals
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Peripheral devices are the elements (components) connected to the system unit so as to assist the
computer satisfy its users
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The cables are
connected to the system unit using connectors called Ports
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Plotter
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- Mouse
- Speakers

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