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Computer Input, Processing, Output and Storage Devices

Understanding the classification of computer input, processing, output and storarage devices in accordance to their function helps students or computer users clearly distinguish between the various components of the computer system.

Computers devices are components that helps to make the computer system interacts within itself and its enviroment. A computer system refers to the computer itself and all other components associate to the functionalities of the computer including human beings operating the computer. Computer devices includes, input, output, processing and storage.


Computer Input is the collection of raw data/facts; hence translating into image, word, sound and action that people understand into a form that the System Unit can understand and process. (e.g. using a form on the website to collect visitor’s opinion, collecting facts about a research project, typing and processing using the computer keyboard or mouse). Computer input can simply be efined as the information entered into a computer system including typed text, mouse clicks, etc.

Computer Input devices are those responsible for the insertion of data into the computer, that is instructing the computer. They are devices that enters information into a computer from an external source. Data is referred to as the “raw material” for information at a particular time.

computer input devices
computer input devices

Examples include; keyboard, mouse, joystick, Webcam, etc.


computer processing device, processor Computer processor or CPU

Computer Processing is the means by which computer programs and instructions are being executed. It is actully the process of transforming input (data) into output (information).

Computer Processing devices are those devices directly responsible for the transformation of data into information. The processor is the main component in the System unit capable of interpreting computer program instruction and processes data. Another vital component for processing is the RAM; It receives and temporary stores data and program instruction to/from the CPU.


Computer Output refers to processed data called information. Output is the process of transmitting the processing data into a form that makes sense to human.

Computer Output devices are those use to display data that has been process either in hardware or software form to make sense to an individual or group of persons. They are simply defined as any device used by a computer to communicate information in a usable form. Information is referred to as the result of processed data which makes sense in life.

computer output devices
computer output devices

Examples includes; printer, monitor, etc.


Computer storage refers to the action of a computer which permits it to store data and information, while computer storage devices refer to those devices responsible for the storing of these data and information. A computer storage devices is a mechanical apparatus that has the ability to store data and also to retrieve this data. Those devices that stores data for a long time are said to be permanent storage devices while those that stores data or information for a short time are referred to as temporal storage devices.

computer storage devices
computer storage devices

Computer storage devices are divided into two;


This refers to those storage devices which are incorporated with the mother board of the system.(the system unit is the box – like structure which contain the processor, RAM, mother board and many other hardware components in the case of a desktop computer). They have small storage capacity.

The constitute the RAM and the ROM.

  1. i)RAM (Random Access Memory)

It stores information temporary for the purpose of processing and loses the information in case of power failure. Hence it is term volatile memory.

As the name implies, information or data stored on this device will be lost in case of power failure. It stores data temporary in order to feed the processor with data to be processed and also stores information temporary after processing before onward storage to a secondary storage (HDD).

This memory can permit information to be read from it and to be written to it.

  1. ii)ROM (read only memory)

This memory stores information permanently. It contains the manuacturer’s information. From the name read only, information on this memory can only be read, it cannot be added, replace or deleted. In clear term read only means the information cannot be edited. This memory is used to store the basic set of information called BIOS (Basic Input, Output System).   It contains information for starting up the computer. The information are said to be hard wired on the mother board of the computer.

Software stored on the ROM are often called firmware because is more like hardware than software.


These are storage devices which have the ability to store data for a long period of time. They can only store data or information but they cannot carry out any control, logical or arithmetic function. Their example includes; Hard disk, Flash disk, Memory card, etc.

These devices are externally attached to the computer system unit or connected to the computer using a bus cable. The most common storage devices are made up of Magnetic storage having large storage capacity and fast access of data ( for hard disk, diskette and tape storage), and Optical storage ( for CD-ROM, WOROM AND DVD). Information on this devices are being stored to be used by a computer user when need be. They will retain their information incase of power failure. They generally have high storage capacity and information or data on it may be edited.

NOTE: Some devices such as digital cameras and touch screen functions both as input and output.

Informative System:

An information processing system is a system which takes information from one form (be it electrical, mechanical or biological) and process (transform) it to another form by an algorithmic process. An example of such system is the computer.

The diagram below clearly explains the input, processing and output devices and how they function. 

block diagram

Block diagram of a computer system showing input, processing, output, and storage components

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