04-07-2012, 12:46 PM
Input Devices
Input Devices .ppt (Size: 718 KB / Downloads: 33)
Input Devices
Keyboard
The keyboard is the most common and widely used input device.
Advantages
Most computers come with a keyboard supplied
People are used to using keyboards to enter data, they need very little training
A skilled typist can enter data very quickly
Specialist keyboards are available e.g. ergonomic, gaming keyboards
Disadvantages
It is easy to make mistakes when typing in data
If you can't touch type, it can be time consuming to enter data
Keyboards are not suitable for creating diagrams
Disabled people often find keyboards difficult to use
Excessive use can lead to R.S.I.
Mouse
A mouse is also called a 'pointing device' because it enables you to control what happens on the screen by moving the mouse on your desk and pointing, clicking and selecting items on the screen
Advantages
Ideal for use with desktop computers
Usually supplied as part of a new computer system
Most computer users are familiar with them and require little training
Works well in conjunction with a keyboard for data entry
Disadvantages
They need a flat space close to the computer
The rollers in mice that use balls can become clogged with grease and grime and lose their accuracy until cleaned.
Overuse can lead to RSI
Touch Screen
A touch screen is the only device which works as both an input and an output device. You view the options available to you on the screen (output) and you then use your finger to touch the option that you have chosen (input).
Advantages
Easy to use - intuitive, don't need much training
No extra peripherals such as a mouse are needed
Software can alter the screen while it is being used, making it more flexible than a concept keyboard which has a permanent overlay.
Disadvantages
Not suitable for inputting large amounts of data
Not very accurate - selecting detailed objects can be difficult with fingers
Tiring to use for long periods
More expensive than alternatives such as a mouse
Not robust - can soon become faulty if misused.
Primary AND Secondary Storage
Primary Storage
Volatile storage, such as RAM, is primary storage
All contents lost when machine switched off
Good practice to make regular back-ups
Secondary Storage
Non-volatile, more permanent storage for software and data files
For example:
Magnetic Tape, Magnetic Disks, CD-ROM, microfilm