3. Methods of input

A person must carry out some physical action in order to provide input information. Various devices and techniques have been developed to allow this.

Keyboard input

This is by far the most common way of inputting data into a computer. An application or program needs to be running to accept the keystrokes. For example a word-processing application or perhaps a command line interface for instructing the operating system.

The user may be entering unprompted data or the computer might have made a specific request for information.

Natural Language

This method involves speaking into a microphone connected to the computer. An application running on the machine takes in the output signal from the sound card and interprets it into digital data. This data may be commands for the computer or they may be direct data to be stored in a file.

For example, a voice activated computer as found in some cars will obey a specific set of commands (e.g. "Radio On"). Also applications such as speech-to-text dictation applications will accept the spoken word and format it into a text file.

The main disadvantage of natural language is that it is still not very accurate especially in the presence of high background noise. It also takes practice to avoid 'Ums' and 'Ahs' when voice dictating.

Touch

The simplest kind of touch interface has been the touch sensitive button.

But this method has really come into its own recently. For many years touch was limited to using a finger to select items on devices such as public information kiosks or through-the-window selection screens at estate agents.

But now tablet computers, smart phones and interactive desk surfaces are making sophisticated use of touch technology. For example placing a finger over a displayed item then skidding it across the screen by simply sliding your finger. Or using two fingers moving away from each other to zoom in on a displayed object.

Movement

The joystick has been the mainstay of movement control but recently far more sophisticated movement sensors have become popular as a game interface.

Holding one of these devices in your hand allows the computer to sense arm swings and other movements. The arm swings are used to control a game or other entertainment application.

There are now computer interfaces that detect arm and leg movements directly without any need to hold a sensor e.g. Kinect

Pointer

The classic pointing device is the mouse. Although there are other devices such as light pens which are also used as a pointing device.

A pointing device is mainly used to select items on screen.

A graphical user interface make extensive use of the mouse as a pointing device.