2.1 - Input hardware:

Input Devices

Keyboard:
This device is mandatory peripheral for any computer. Its alphanumeric keys derived from traditional typewriter and are used to enter text strings, while additional keys such as arrow and function keys, performs special actions.

 
Mouse:
This is an example of pointing devices which input spatial data to the computer. As mouse is moved by user’s hand on a flat surface, a mechanical ball or optical sensor at its base signals the amount of movement to the computer which correspondingly moves a cursor on the screen. The user determines the location of the cursor. Mouse is more than just a pointing device, it has buttons each of which can be clicked to give binary input.

 
Touchpad:
Another 2D point device, particularly common on portable computers, the touchpad is a small rectangular area embedded with electronic sensors to determine the position of a touching finger or stylus. The movement of the finger or stylus is echoed by the movement of the cursor.

 
Pointing stick:
It is another 2D pointing device common on portable computers, the pointing stick is typically a rubber peg located between ‘G’, ‘H’ and ‘B’ keys, which moves the cursor in response to pressure applied with a finger.

Trackball:
This is essentially an upside down mouse with a socket containing a ball which the user manipulates with his hand to make the cursor move.

Spaceball:
This is a pointing device with six degrees of freedom versus the two of an ordinary mouse. It is used in special applications such as manipulating a camera in a 3D scene: not only is the camera moved but also rotated, affording it multiple degrees of freedom, each of which the user controls. The spaceball itself consists of a pressure sensitive ball which can distinguish different kinds of forces, including backward/forward, lateral and twist, responding by moving and orienting the selected object.

Tablet:
This is a digitizing device which has a surface embedded with sensors to pick up the successive coordinates of a stylus head or fingertip as it travels over the surface (in effect converting physical motion into digital data). The user can write or draw on a tablet, just as on paper with pen, the output being displayed on the monitor. The monitor is usually separate but on devices like tablet PC, the display and sensing surface are the same.

Haptic device:
This is a pointing device which gives physical feedback to the user based on the location of the cursor or possibly, that of an object being moved along with the cursor. The functioning of heptic device is like a mouse with a mechanical ball which is programmed to lock and stop rolling when cursor reaches the side of the screen. The reaction of user then has is of that cursor running into physical obstacles at the edge of the screen. The three-link arm swiveling on a ball gives it six degree of freedom. Haptics can be used on teleoperation of robots and simulated surgery training in medicine

Joystick:
This is an input device popular in video games and applications such as flight simulators. A joystick pivots around a fixed base, gaining thus two degrees of freedom. Usually, it has buttons which can provide additional input. In a game or simulator setting joystick is typically used to control object traveling through space.

Wheel:
This is also an input device for games and simulators obviously derived from the car steering wheel and provides rotational input in an exactly similar manner generally to the virtual automobiles. Haptic feedback to give the user a sense of vehicle’s response and even of the terrain over which it is traveling, is becoming increasingly popular.

Camera:
This is a input device to capture images from surroundings. It also provided software to recognize faces, gestures and expressions.