An Overview Of Computer System

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Last Updated on November 23, 2020 by admin

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Definition of Computer

Computer can be defined as a device, which under the control of a stored program, can accept data in a prescribed form, process the data and supply the results as information in a specified form. Not that alone, a computer is an electronic and electromechanical device that can accept, process, store and retrieve the data as well as output the result by following a set of instructions called a Program. More so, a computer can be defined as a programmable electronic device designed for performing prescribed operations on data at high speed, especially one housed with or linked to other devices for inputting, storing, retrieving, and displaying the data.

The three principal characteristics of a computer are:
1.It consists of electronic and electro-mechanical parts working together to process data
2.It responds to a specific set of instructions in a well-defined manner can execute a prerecorded list of instructions (a program).


A Computer system includes all the other things that make the computer to function. It consists of three major parts, namely:
  • Computer Hardware
  • Computer Software
  • People ware / Human ware


Computer hardware is the collection of physical elements that constitute a computer system. Computer hardware refers to the physical parts or components of a computer such as monitor, keyboard, hard drive disk, mouse, CPU (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that you can actually touch.
Computer hardware is divided into two main categories namely:
  • System unit, and
  • Peripherals
The System Unit is the electronic components such as CPU, primary memory and other devices that are used to process and store data, It is the computer casing or cabinet that contains the Central Processing Unit (CPU) and many other electronic components. It contains many hardware components that can be seen only when the case or cabinet is open.
A Peripheral device is any piece of hardware attached to the computer’s system unit to facilitate or enhance input and output operations. Those devices which are not an integral part of the CPU are referred to as being peripherals. These attachments increase the capabilities of the computer . Peripherals are usually used for either input, storage, output and communication devices (such as a hard disk, keyboard, printer, modems, digital camera, etc.).
Fig 1: The main hardware components of a computer system
Input devices are hardware devices which take information from the user of the computer system, convert it into electrical signals and transmit it to the processor. The primary function of input devices is to allow humans to interact with the computer system. For instance a mouse allows the user to control the movement of the pointer (a common element in user interface design).
Output devices take data from the computer system and convert it to a form that can be interpreted by humans. For instance a monitor creates a visual electronic display to output information created by the processor to the user.
Processing devices are the components responsible for the processing of information within the computer system. This includes devices such as the CPU, memory and motherboard.
Storage devices are components which allow data to be stored within a computer system. This includes devices such as hard disk drives and compact disk drives.
Computer software is a set of instructions (programs) that commands the computer hardware what to do, how to do and as well as when to do. In other words, software is a set of programs, procedures, algorithms and its documentation. It is the driver of the hardware. Without the software, the computer becomes useless and an idle piece of metal.
In contrast to hardware, software is intangible, meaning it ‘it cannot be touched’.
Software as a whole can be divided into a number of categories based on the types of work done by programs. The two primary software categories are;
  • System software: This is a collection of computer software designed to operate the computer hardware and to provide and maintain a platform for running application software. It is made up of Operating system, device drivers, servers, utilities which control the workings of the computer.


  • Application software:  also known as software application, application or app, consists of programs that instruct the computer to accomplish specific tasks for the user, such as word processing, operating a spreadsheet, managing accounts in inventories, record keeping, or playing a video game. These programs, called applications, are run only when they are needed. The number of available applications is as great as the number of different uses of computers. Some examples of this category of software includes;


  • Accounting software e.g. Peachtree Complete Accounting
  • Computer-aided design e.g. Corel Draw
  • Databases e.g. Microsoft access
  • Decision making software e.g. Microsoft project
  • Educational software e.g. Microsoft Encarta
  • Image editing e.g. Adobe photo-shop
  • Mathematical software e.g.  SAGE
  • Word processor e.g. Microsoft word
  • Spreadsheets e.g. Microsoft excel
  • Media players and database applications


(i)  Can run independently of the application software
(i)  It cannot run without the presence of the system software
(ii)  It gets installed when the operating system is installed on the computer
(ii)  It is installed according to the requirements of the user
(iii) They are programs that run and control the hardware units of the system
(iii)  They are programs designed to meet specific needs of users
(iv) It provides a platform for running the application software
(iv)  It helps the user to perform single or 
multiple tasks
(v)  Some examples of system software are computer operating systems like Windows XP, Linux, Mac, Os and Ubuntu
(v)  Some examples of application software are Microsoft Word, Accounting software like Microsoft Excel and Microsoft Access
(vi) They are intricately(carefully) programmed by system programmers
(vi)  They are programmed by applications programmers.
The following are the major characteristics of a computer, depending on their types and application:
A computer is a very fast device. It can carry out instructions at a very high speed obediently, uncritically and without exhibiting any emotions. It can perform in a few seconds the amount of work that a human being can do in an entire year – if he work day and night and is nothing else.

Some calculation that would have taken hours and days to complete otherwise, can be completed in a few seconds using the computer. The speed of computer is calculated in MHz, that is one million instructions per second.

 • Accuracy 
Accuracy of a computer is consistently high and the degree of accuracy of a particular computer depends on the instructions and the type of processor. But for a particular computer, each and every calculation is performed. For example, the computer accurately give the result of division of any number up to 10 decimal points.

 • Versatility 
Versatility is one of the most wonderful things about computer. Multi-processing features of computer makes it quiet versatile in nature. One moment, it is preparing the results of particular examination, the next moment it is busy preparing electricity bills, and in between it may be helping an office secretary to trace an important letter in seconds.

It can perform different types of tasks with same ease. All that is required to change its talent is to slip in a new program into it. Briefly, a computer is capable of performing almost any task provided that the task can be reduced to a series of logical steps.

 • Reliability 
 Computer provide very high speed accompanied by an equality high level for reliability. Thus computers never make mistakes of their own accord.

 • High Storage and Retrieval Capacity
A computer can store and recall any amount of information because of its secondary storage capability. Every piece of information can be retain as long as desired by the user and it can be recalled information almost instantaneously. Even after several years, the information recalled will be as accurate as on the day when it was fed to the computer.

 • Diligence 
The computer is a machine, does not suffer from the human traits of tiredness. Nor does it loses concentration even after working continuously for a long time.

This characteristics is especially useful for those jobs where same tasks is done again and again. It can perform long and complex calculations with same speed and accuracy from the start till the end.

 • Storage
The computers have a lot of a storage devices which can store a tremendous amount of data. Data storage is essential function of the computer. Secondary storage devices like floppy disk can store a large amount of data permanently.
.  Automation
Once the instructions are fed into computer it works automatically without any human intervention until the completion of execution of program until it meets logical instructions to terminate the job.
  • A Handbook on Computer Studies / ICT for Senior Secondary Schools,  SS 1 by Niyi Adekolegan et al
  • Evans Computer Science for Senior Secondary Schools 1 by A.C. Akukwe et al
  • HiiT @ School, Computer Studies for Senior Secondary Education
Author: Simnify

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