Assignment 1Input device (keyboard and computer stress injury)
| November 18 2011
Q1. How are keys pressed on a keyboard interpreted correctly by the computer? (How does a keyboard communicate with the CPU?) Q2. Describe common keyboard shortcuts that you can use (using the keyboard modifier key, and function key) to ease every day computing operations? Q3. How can you avoid computer related repetitive stress injuries?
| Roll no 11060819-020 , 11060819-06 ,11060819-018
Input device (keyboard and computer stress injury)
Q1. How are keys pressed on a keyboard interpreted correctly by the computer? (How does a keyboard communicate with the CPU?)
A tiny computer chip, called the keyboard controller or keyboard bios, that a key has been pressed. The keyboard controller places a code into a part of its memory, called the keyboard buffer, indicating which key was pressed. This code is called the key’s scan code. The keyboard controller then signals the computer’s system software that something has happened at the keyboard. It does not specify what has occurred, just that something has. The signal the keyboard sends to the computer is a special kind of message called an interrupt request using an IRQ address. The keyboard controller sends an interrupt request to the system software when it receives a complete keystroke. For example, if you type the letter "r", the controller immediately issues an interrupt request. (If you hold down the Shift Key before typing "R", the controllers wait until the whole key combination has been entered.)
En the system software receives an interrupt request, it evaluates
When the system...
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