What mask in register F would cause the instruction 7AAF (refer to the language description table) to put a 1 in the most significant bit of register A without disturbing the other bits?
A) 11111110
B) 00000001
C) 10000000
D) 011111111

Question

Quizplus · Accepted Answer

The instruction 7AAF is an arithmetic shift left which shifts all the bits of register A one position to the left, padding with a 0 on the right and placing the original most significant bit in the carry flag. To put a 1 in the most significant bit of register A without disturbing the other bits, we should use a mask that only sets the most significant bit to 1 and leaves the rest as 0s. This can be achieved by using the mask 10000000, which will only modify the most significant bit when performing the shift operation.

What Mask in Register F Would Cause the Instruction 7AAF