Negative logic viewpoint – can a NAND gate implement the behavior of a negative-OR (i.e., OR with inverted signal senses)?

Introduction / Context:
Universal gates such as NAND are powerful because they can realize a variety of logic functions under different signal conventions. In negative logic, the logical meaning of 0/1 is swapped (low = asserted, high = deasserted), which changes how we interpret familiar gates. This question asks whether a NAND gate corresponds to a negative-OR function under that convention.

Given Data / Assumptions:

• Inputs and/or outputs may be interpreted under negative logic (active-LOW).
• Device is an ideal NAND gate with standard Boolean behavior.
• No analog limitations (fan-in, thresholds) affect the logical equivalence.

Concept / Approach:
In positive logic, NAND(A,B) = NOT(A * B). Under negative logic interpretation, complementing input and output senses maps NAND to OR. Intuitively, if low level “means” true, then a NAND’s output low occurs precisely when either input is low-true, aligning with OR semantics in the negative domain. This is a classic duality used in logic families and active-LOW signal design.

Step-by-Step Solution:

Verification / Alternative check:
De Morgan’s law confirms NOT(A * B) = NOT(A) + NOT(B). Interpreting inputs as active-LOW means the gate acts like OR on the active meanings. Textbooks present NAND as negative-OR and NOR as negative-AND under signal inversion conventions.

Why Other Options Are Wrong:
Claims about Schmitt triggers, low frequency, or CMOS-only are hardware distractions; the equivalence is logical and independent of device technology or speed regime.

Common Pitfalls:
Mixing physical voltage levels with logical meaning. Remember that changing the active sense (positive vs negative logic) changes the interpretation of the same hardware function.

Final Answer:
Correct