Lec. 9 : Input Units (Keyboard, Mouse, and Touch screen)

Input Units (Keyboard, Mouse, and Touch screen)
An input device is any hardware device that sends data to a computer, allowing you to interact with and control the computer. Examples of input devices include keyboards, mouse, scanners, digital cameras and joysticks, light pens, etc.
1. Keyboard
The most common input device is the keyboard. It is standard equipment on virtually every personal computer, keyboard is an device used to convert the keystrokes in to the electrical signals that a computer can understand. There are special types of switches and circuits to do this. Keyboard contains its own internal processor that takes electrical signals through key strokes.

The microprocessor and controller circuitry of a keyboard.
The basic elements of a keyboard are a switch matrix (key matrix) and a keyboard interface encoder chip. The switch matrix consists of a number of horizontal and vertical lines crossing each other, at each crossing, a small switch operated by a spring –loaded key is located. The keyboard encoder is a microprocessor with an in-built ROM.