Which mode of 8253 is used for square wave generation:

8253/54 can be operated in 6 different modes:

a. Mode 0:

It is used to generate an interrupt to the microprocessor after a certain interval.

b. Mode 1:

It can be used as a mono stable multi-vibrator.

c. Mode 2:

- This is called rate generator

- The output is normally high after initialization

- Whenever the count becomes zero, another low pulse is generated at the output and the counter will be reloaded

d. Mode 3:

This mode is used for square wave generation

e. Mode 4:

- This is known as software triggered interrupt

- In this mode, the output will remain high until the timer has counted to zero, at which point the output will pulse low and then go high again

f. Mode 5 :

- This is hardware triggered mode

- This mode generates a strobe in response to an externally generated signal