NOR gate and negative logic equivalence A 2-input NOR gate implements the complement of the OR function. Under negative-logic interpretation, a 2-input NOR is equivalent to which gate?

Introduction / Context:
Logic functions can be reinterpreted under negative logic (active-low signals), where a LOW represents logical 1. De Morgan’s theorems show powerful equivalences between gates when inputs and/or outputs are inverted, enabling flexible implementations using universal gates such as NAND or NOR.

Given Data / Assumptions:

• 2-input NOR with output Y = ~(A + B).
• Negative-logic interpretation (active-low inputs/outputs).

Concept / Approach:
In negative logic, the logical meaning of levels is swapped. De Morgan’s law states: ~(A + B) = (~A) * (~B). If A̅ and B̅ are viewed as active-low forms of A and B, a NOR gate acts like an AND function in negative logic. Thus, a 2-input NOR is equivalent to a negative-AND gate.

Step-by-Step Solution:

Verification / Alternative check:
Truth table mapping confirms that NOR outputs HIGH only when both A and B are LOW. In negative logic, LOW = 1, so the gate outputs logical 1 only when both logical inputs are 1, matching AND behavior.

Why Other Options Are Wrong:

• Negative-OR: Would correspond to NAND behavior, not NOR.
• Negative-NAND: Not the proper equivalence for a simple NOR.
• None of the above: Incorrect because negative-AND is correct.

Common Pitfalls:
Forgetting that negative logic reinterprets levels; applying De Morgan incorrectly; mixing symbol inversion (bubbles) with algebraic inversion without consistent logic mapping.

Final Answer:
negative-AND gate