Briefly explain any 4 modes of operation of the 8254 interval timer.

Briefly explain any 4 modes of operation of the 8254 interval timer. (06-12-2012)

Briefly explain any 4 modes of operation of the 8254 interval timer.



The following are the modes of operation of the programmable timer 8254:

- Mode 0: Also known as the interrupt on terminal count. In this mode the output is initially low. Once the count of terminal is reached the output becomes high.

- Mode 1: Programmable one shot is also known as the hardware triggered one-shot. For it to happen, the count registers must be loaded and the A 0-1 pulse has to be sent to the Gate input in order to trigger the counter.

- Mode 2: Rate generator, this process is repeated indefinitely.

- Mode 3: Square wave generator, when gate=1, The out is a square wave where the high pulse is equal to the low pulse of N is an even number. In case the N is an odd number the high pulse is longer. The mode-3 is commonly used for as frequency divider.
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