The keys in Keyboard act as mechanical levers to input charaters and commands for computers. Keyboard is used to type text and numbers into a word processor. A keyboard is also used to give commands to the operating system of a computer, such as Windows' Control-Alt-Delete combination, which brings up a task window or shuts down the machine.

The Matrix Circuit
Keyboards use a matrix with the rows and columns made up of wires. Each key acts like a switch. When a key is pressed, a column wire makes contact with a row wire and completes a circuit. The keyboard controller detects this closed circuit and registers it as a key press.

Single Key Press : The A Key is Pressed

Multiple Key Press : The A & D Keys are Pressed


Three Simultaneous Key Presses