Introduction to Computers Tutorial

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Computer: A computer is an Electronic device that processes Data electronically to produce
Data: can be defined as raw facts & figures about a task, a project or a research being carried out

Information: this is the results of data processing, otherwise referred to as fully refined
A computer system is made up of two significant units I.e.
1. Hardware
2. computer Softwares

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1. Hardware

Hardware can be defined as all tangible components making a computer system and can be illustrated by the following block Diagram

Input Units

This comprises of all the physical elements used for data entry


  • Keyboard
  • Mouse
  • Scanner: used to feed pictorial data into the computer
  • Plotter: used for drawing maps
  • Joystick: provide motion, generally used for playing games

Processing Unit
OUTPUT units
o Bar Code Reader: used in wholesale/retail, e.g. supermarkets to capture data in the bar code

Output Units

This comprises of all the tangible components used to give out data / Information from the
computer system.


  • Monitor
  • Printer
  • Speakers etc
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Central Processing Unit (System Unit)

The central processing unit is compared to a ‘HEART’ in the human person, and it coordinates all processing
activities & ensures smooth interaction between all the hardware, without which results in its

Backing Storage

Can be mainly divided into two
i. Primary storage
It’s used to hold programs and data temporarily when they are being used. It’s referred to as RAM (Random Access Memory). It is seen as a ‘scratchpad,’ where all data is manipulated during processing / where all processing cycles take place.

The bigger this memory is the more programs you can run at any given time. When the computer is
switched off the content of RAM is lost (it is volatile).
ii Secondary storage
It’s used to store data permanently until they are needed for use later; an example of this is the hard-disk drive. When information is saved, it’s written on the hard drive and retrieved from there when needed (read).

In addition to hard drives, other secondary devices include floppy disks (diskettes), magnetic tapes, CD-ROM, Flash disks, DVD’s, etc.

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Software is all program designed to operate a computer system and gives ‘Live’ to the system.
A program is a set of instructions/commands written in a language known to the computer telling the computer what to do, for the successful completion of a task.
Softwares can broadly be classified into two
a. System software.
b. Application software

a. System software

These are programs concerned with the effective operation of the Computer system, otherwise referred
to as Operating system.
Examples of operating systems are:
Windows 95 / 98 / XP / Vista etc
Mac Os
Windows Nt / 2000
Unix / Linux

b. Application software

These are software developed to handle the organization-specific requirement, i.e. they are written to
solve organization particular interests/problems.
The two classes of application software include:-
i) Application packages-
These are programs that are developed and supplied by computer manufacturers, software
house, or bureau at a price. They are ready-made programs that ca be ruddily purchased by
the user. They cover standard business functions and have different applications.

Examples are:

  • Word Processors:- used for the preparation of documents, e.g. Ms. Word
  • Spreadsheet:- used for manipulation of numerical data, e.g. Ms. Excel
  • Database Management System:- used for record management, e.g. Ms. Access
  • Presentation programs:- used for creating outputs for presentation, e.g. Ms. PowerPoint
  • Desktop Publishing Programs:- used for creating publications, e.g. Ms. Publisher

ii) User Application programs (specialists application software)

These are programs designed to meet specifications of the user; they are not ready-made but
Are made on request by programmers or software houses. They sometimes take time to

  • Supermarket application
  • School management application
3. Diagnostic Programs

These programs are designed to help troubleshoot for problems with a computer system
· Utility Programs
· Antiviruses


· It is automatic- it works with minimum human intervention once supplied with the
necessary data and instructions.

  • Data processor- it processes raw facts to become information.
  • Storage device- it stores information for later reference.
  • Electronic- it requires some form of power to drive it.

  • Speed:- performs tasks in concise periods (in comparison to working manually)
  • Consistency: – creates the same results given the same data and instructions.
  • Secrecy:- information is reasonably protected if the computer system is well managed
  • Versatility: – can do the same thing over and over again without being worn out.
  • Saves space:- computers store large chunks of information in limited space therefore
    becomes space economical
  • Efficient and Accurate:- they have minimal chances of making mistakes if the data and
    instructions are correct
  • They are flexible, i.e. can adapt to any workload without much strain.

  • Computers are expensive
  • Cuts down on employment opportunities
  • Need expertise, which is costly to hire and maintain
  • They create eye problems
  • Loss of information if not well managed
  • Weather Forecasting
  • Mathematic and statistical analysis
  • Design Work
  • Medical Diagnosis
  • Education
  • Business


Computers can be classified into the following
i) Mainframe computers
It’s a large and powerful computer which is a general-purpose. It has a range of input and output
Devices and in most cases several CPUs. It’s a costly computer.
ii) Mini-computers
They can be described as a scaled-down version of the mainframe. They also have a range of input and
Output devices.
iii) Microcomputers

  • Are small in size, cheap, general-purpose computers.
  • They are mostly used in small size businesses for type-setting, graphic designing, and publishing.
  • Most commonly referred to as Personal computers (PCs) since they support a single user at any

Given time.

A Supercomputer is a computer that is at the frontline of current processing capacity, particularly
Speed of calculation. Supercomputers are used for highly calculation-intensive tasks such as problems
including weather forecasting, climate research, molecular modeling (computing the structures and
properties of chemical compounds, biological macromolecules, polymers, and crystals), and physical
simulations (such as simulation of airplanes in wind tunnels, simulation of the detonation of nuclear
weapons, and research into nuclear fusion).
NB: The trend in computer technological revolution is that there has been;
i) Continual decrease in computer size
ii) Increase in processing speed
iii) Improved power of processing
iv) Lesser power consumption
v) The reduction in their related facilities, e.g. cost
vi) Number of component per circuit IC significantly increased, e.g., transistors, capacitors, diodes, etc
per chip.

Computer crimes

These are criminal acts that are done using computers
Its takes the following forms
i) computer piracy – it is illegal copying of personal software / Illegal duplication
ii) Sale of copyrighted software, often in shape to make the product appear legitimate.
iii) Soft lifting:– it’s a form of piracy that occurs when extra copies of a program, e.g. games are
Made within an organization for employees to use. Disk swapping among friends and
colleagues are also included in this category of swapping.

Data security and control

Computerized systems are critical to organizations and companies of all kinds and therefore
the security of information is vital.
The computers themselves are not always an essential part. However, in most cases the
organization’s information stored in the network and the programs which process that information
are more important.
Threats to computers and data security are classified as either internal or external threats.

External threats

  • Fire, floods, earthquakes, and other natural disasters are potential threats to computers
    but not the most common.
  • Theft of equipment, e.g. PC’s, CPU, printers, and even memory chips after a break into a building (these are some of the most common).
  • Espionage (intelligence): this refers to the illegal handling of information to be used for some predefined purpose. E.g., access to a payroll or accounting information should be restricted; thus, such information should be shielded away fro external and internal spies.

Internal threats
The internal threats include;

  • Virus-these is programs developed with the intention to destroy the computer systems.
  • Hacking-these refers to illegal access of information to be used in other businesses instead of
    the one intended.
  • Hardware failure-this refers to the computer system, not working as expected due to technical
  • Fraud-it is access to information to carry out illegal business.
  • Corruption of databases-it refers to the files that store instructions, commands and even
    information failing to operate as expected or instead of being not available(it also referred to as
    software failure)

Control measures:

1) Introducing passwords and creating access levels. This is so that departments are only allowed to access
data of that particular department with the supervisor accessing and controlling all the data.
2) Backing-up data often and keeping many back-up copies in different locations.
3) Reinforcing the doors and windows in the computer rooms to act as an anti-burglary measure.
4) Installing anti-virus software and regularly updating them.

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