Input Devices

In computing, an input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Examples of input devices include keyboards, mouse, scanners, and digital cameras

Keyboard

There is no standard computer keyboard, although many manufacturers imitate the keyboards of PCs. There are actually three different PC keyboards: the original PC keyboard, with 84 keys; the AT keyboard, also with 84 keys; and the enhanced keyboard, with 101 keys. The three differ somewhat in the placement of function keys, the Control key, the Return key, and the Shift keys.

Mouse

There are three basic types of mice:

Mechanical: Has a rubber or metal ball on its underside that can roll in all directions. Mechanical sensors within the mouse detect the direction the ball is rolling and move the screen pointer accordingly.

optomechanical: Same as a mechanical mouse, but uses optical sensors to detect motion of the ball.

optical: Uses a laser to detect the mouse's movement. You must move the mouse along a special mat with a grid so that the optical mechanism has a frame of reference. Optical mice have no mechanical moving parts. They respond more quickly and precisely than mechanical and optomechanical mice, but they are also more expensive.

Touch Screen

A touch screen is an electronic visual display that the user can control through simple or multi-touch gestures by touching the screen with one or more fingers. Some touch screens can also detect objects such as a stylus or ordinary or specially coated gloves. The user can use the touch screen to react to what is displayed and to control how it is displayed (for example by zooming the text size).

 The touch screen enables the user to interact directly with what is displayed, rather than using a mouse, touchpad, or any other intermediate device other than a stylus, which is optional for most modern touch screens.