As discussed in computer systemshardware is also a component of a computer which consists of sub units as outlined in previous post.

Here I shall  discuss hardware devices categorised under a sub unit called input devices.

Input devices

These devices are used as a mode of converting human readable input to machine language that a computer can understand/ process. They also can be classified into keying, pointing, scanning, touch screens & voice input devices. 

1. Keying devices

they are used to convert typed numbers and letters and special symbols into machine language for processing. The following are types of keying devices:  

  • traditional keyboard –is a rigid and commonly used keyboard
  • flexible key board – it is portable and can be folded.
  • key pad – a miniature keyboard used on portable devices such as mobile phones
  • Braille key board – designed for use by the blind.
  • ergonomic Keyboard –designed to provide comfort for wrist.

2. Pointing devices

are devices used to control a pointer/ cursor on the screen. They include: 

  • mouse 

 a small rodent like device with two buttons and a cableb on its ‘head’. It is moved on a farely smooth surface so as the movement is interpreted to the position of the pointer on the screen. 

  • track ball 

works like a mouse however instead of moving it on the surface, a ball located on its top is rotated, some laptops come with it integrated on them. 

  • Joystick 

 looks like a lever, thought used to control pointer on the screen, its main purpose playing computer games. 

  • Light pen 

works by detecting the command or item illuminated by it. 

  • Stylus 

is used on devices like PDAs that recognize handwritten data.

NB: mouse can be classified into: standard mouse, optical mouse and cordless mouse.

3. Scanning devices

Before discussing these devices, understanding the meaning of introductory terms is important. To begin with: 

scanning is capturing data from an object and converting it into digital format where as a Scanner is an input device that captures data from source documents and objects. 

Scanners therefore can generally be classified as either magnetic or optical scanners.

  • Optical scanners 

They capture data using optical/ light technology. A light beam passes over an object and the image is analysed by specialised software. Examples include: 

Optical Mark Recognition Scanner

detects marks made on a piece of paper using ink or pencil. 

Optical Barcode Recognition Scanner 

capture data coded as lines of varying thickness known as universal product codes. 

Optical Character Recognition Scanners 

reads type written, computer printed, hand written characters and transforms the image into a softcopy that can be manipulated by word processor.

  • Magnetic scanners 

These scanners capture data written using magnetic ink or coded on to a magnetic strip. They include:

 magnetic ink character recognition

reads characters written using magnetic ink e.g. cheque. 


also known as graphic tablet, it allows one to draw an image using a stylus however the image drawn does not appear on it but on the computer screen. 

Digital camera 

like any other camera the capture images but their images are stored digitally on a memory card. 

Other input technologies include:

4.     Touch screens consists of infrared light criss-crossing behind it so when a user touches a location on the screen s/he interrupts the light and the output is displayed on the screen. 

5.      Interactive white board

also known as a smart board, is a large interactive display board connected to a computer where by the user controls it by writing using a light pen or finger on the board. 

6.     Voice input

is an input technology where a microphone is used to enter data inform of speech into a computer. Is most suitable method for physically challenged individuals however it does not support speech related problems such as accents. 


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s