Question

To set the bits of a register R1 to 1, we must OR the contents of the register with?

(a) 00H

(b) 11H

(c) FFH

(d) 0FH

This question was addressed to me in an interview.

My query is from Arithmetic and Logic Instructions in section AVR Microcontroller of Microcontroller

Answer 1

Correct choice is (c) FFH

To explain I would say: To make the contents of the register R1 to 1 we must OR the contents of that register with FFH because according to Or algorithm 0+1=1 and 1+0=1.