Posted by : Waqas Javed Saturday, 27 September 2014

Working of keyboard

How computer takes input from keyboard

The process of taking input from keyboard is accomplished in 5 steps. It is not actually the case that you enter key on keyboard and cpu just know it that which key you have pressed.

1. You press a key on keyboard it activates the connection of that key circuit.

2. That circuit sends a specific scan code particular to every key from memory of keyboard called keyboard controller to the its part of memory called keyboard buffer.

Keyboard controller is that part of keyboard memory in which all scan codes of every key is already stored.

Keyboard buffer saves the scan code of that key which was pressed. It can save many keys code at once.

3. Keyboard controller sends an interrupt request to the sys. software.

4. The system software respond to the interrupt by reading the scan code from buffer.

5. System software passes this scan code to the CPU which processes the code according to the application software and performs the function.

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