JOMO KENYATTA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY
DIT 0204 (DIT0204)
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Class notes DIT 0204 (DIT0204)
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DIT 0204 (DIT0204)
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JOMO KENYATTA UNIVERSITY OF AGRICULTURE AND TECHNOLOGY
Get ahead in math by solving these real-world and fun-to-do word problems.Math by Example is an excellent resource of various math word problems.It is known that success on aptitude test like the SAT is directly tied to one's ability to solve word problems. This book was written with the intent of ...
, INTRODUCTION TO COMPUTERS
Definition of a Computer:
An electronic device that accepts data as input, and transforms it under the influence of a set of
special instructions called Programs, to produce the desired output (Information).
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.
Note: -
A computer is described as an electronic device because; it is made up of electronic components
and it uses electric energy (such as electricity) to operate.
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.
It works on the data using the instructions issued, means that, the computer cannot do any useful
job on its own. It can only work as per the set of instructions issued.
Program: A computer Program is a set of related instructions written in the language of the
computer & is used to make the computer perform a specific task (or, to direct the computer on what
to do).
Data: Data is a collection of raw facts, figures or instructions that do not have much meaning to the
user.
Data may be in form of numbers, alphabets/letters or symbols, and can be processed to produce
information.
Types of Data
There are two types/forms of data:
a). Digital (discrete) data: Digital data is discrete in nature. It must be represented in form of
numbers, alphabets or symbols for it to be processed by a computer. Digital data is obtained by
counting. E.g. 1, 2, 3 …
b). Analogue (continuous) data: Analogue data is continuous in nature. It must be represented in
physical nature in order to be processed by the computer. Analogue data is obtained by
measurement. E.g. Pressure, Temperature, Humidity, Lengths or currents, etc
Data Processing: This is the process of collecting all items of data together & converting them into
information.
,Processing refers to the way the data is manipulated (or handled) to turn it into information. The
processing may involve calculation, comparison or any other logic to produce the required result. The
processing of the data usually results in some meaningful information being produced.
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. The information must be accurate,
timely, complete and relevant.
Comparison between Data and Information
Data Information
1. Unprocessed (raw) facts or figures. 1. It is the end-product of data processing (processed data)
2. Not arranged in meaningful format. 2. Arranged into a meaningful format.
3. Does not have much meaning to the user. 3. More meaningful to the user.
4. Cannot be used for decision-making. 4. Can be used to make decisions.
Characteristics / Features of a Computer
1. Speed-Computers operate at very high speeds, and can perform very many functions within a
very short time.
2. Accuracy: Unlike human beings, computers are very accurate, i.e., they never make mistakes. A
computer can work for very long periods without going wrong. Usually errors are committed by
the users entering the data to the computer, thus the saying Garbage in Garbage Out (GIGO).
This means that, if you enter incorrect data into the computer and have it processed, the computer
will give you misleading information.
3. Reliability-The computer can be relied upon to produce the correct answer if it is given the
correct instructions & supplied with the correct data.
4. Consistency: Computers are usually consistent. This means that, given the same data & the
same instructions, they will produce the same answer every time that particular process is
repeated.
5. Storage: A computer is capable of storing large amounts of data or instructions in a very small
space. 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.
6. Diligence: Unlike human beings, a computer can work continuously without getting tired or
bored. 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.
7. Automation: A computer is an automatic device. This is because, once given the instructions, it
is guided by these instructions and can carry on its job automatically until it is complete
, 8. Versatile: A computer can be used in different places to perform a large number of different jobs
depending on the instructions fed to it.
Review Questions.
1. What is a Computer?
2. Why is a computer referred to as an electronic device?
3. Define the following terms as used in computer science.
a). Data. c). Data processing.
b). Programs. d). Information.
4. (a) Briefly explain the two forms of data.
(b) Give THREE differences between Data and Information.
5. What does the term GIGO stand for?
6. List and explain 4 salient features/ properties of a computer.
PARTS OF A COMPUTER
A computer is made up of a collection of different components that are interconnected together in
order to work as a single entity. A Computer consists of the following parts/devices: -
a) The System Unit. c) Output devices.
b) Input devices. d) Storage devices.
System Unit This is the casing (unit) that houses electronic components such as the ‘brain’ of the
computer called the Central processing Unit (CPU) and storage devices. The components in the
System unit include:
➢ Central Processing Unit (CPU), which is also referred to as Processor.
➢ Motherboard.
➢ Power supply unit.
➢ Memory storage devices.
➢ Disk drives, which are used to store, record and read data.
Types of System units
There are two makes of System units:
a) Tower style system unit. This system unit is made to stand alone. They are designed to be placed
on the floor. Tower style units have more space for expansion than the typical desktop units.
b) Desktop system units. Desktop units lie on the desk with the monitor resting on top of the system
unit.
Features of the System unit
✓ It houses the CPU
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