The mask logical micro operation is equivalent to which logical gate?

Masking is a bitwise operation that selectively keeps or clears the bits of a data word using a fixed mask pattern: wherever the mask bit is 1, the data bit is retained unchanged, and wherever the mask bit is 0, the data bit is forced to 0. This “output 1 only when both the data bit and the mask bit are 1” rule is exactly the AND gate's truth table, so masking is implemented as a bitwise AND between the data and the mask.

1. Take the data byte 1011 0110 and the mask byte 1111 0000 - the mask marks the upper nibble to be kept and the lower nibble to be cleared.

2. AND each bit position: for the upper nibble, 1&1, 0&1, 1&1, 1&1 all equal the original data bits (1, 0, 1, 1); for the lower nibble, 0&0, 1&0, 1&0, 0&0 all equal 0.

3. The result is 1011 0000 - the upper nibble survives unchanged and the lower nibble is cleared to zero, exactly the masking behaviour described above.

• An OR gate can only push bits toward 1, so it can never clear the masked-out bits to 0 - it fails the 'clear on mask=0' requirement.

• A NOR gate inverts the OR result, so it would flip the retained bits instead of leaving them unchanged - it fails the 'keep on mask=1' requirement.

• A NAND gate inverts the AND result, so it would invert exactly the bits masking is supposed to preserve - the opposite of what is needed.

Only the AND gate's truth table satisfies both rules - retain the bit when the mask is 1, clear it when the mask is 0 - so the mask logical micro operation is equivalent to an AND gate.