Question

Which of the following command is used to make all the internal registers of 8237 clear?

(a) clear first/last flipflop

(b) master clear command

(c) clear mask register

(d) none of the mentioned

The question was asked during an interview.

I'd like to ask this question from Programmable DMA Interface 8237 -2 in section DMA, Floppy Disk and CRT Controllers of Microprocessor

Answer 1

Right answer is (b) master clear command

Explanation: Using master clear command, all the internal registers of 8237 are cleared, while all the bits of the mask register are set.