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.
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:
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.
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.
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.
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.