Identifying a gate from inhibit behavior If a signal passing through a gate is inhibited by applying a LOW to one input, yet the output remains HIGH, the gate is which type?

Introduction / Context:
Many digital designs use gating or enabling signals. Recognizing how a gate reacts when an input is forced LOW helps identify the gate from observed behavior and is valuable for troubleshooting with a logic probe or oscilloscope.

Given Data / Assumptions:

• An input is driven LOW to inhibit a signal path.
• The observed output under this condition is HIGH.
• Positive logic is assumed (LOW = 0, HIGH = 1).

Concept / Approach:

NAND is the inversion of AND: Y = (A · B · ... )’. An AND gate forced with any LOW input yields 0 at its output. Inversion by NAND flips that to 1. Therefore, whenever any input is 0, a NAND gate outputs 1. Only when all inputs are 1 does a NAND output 0. This matches the stated inhibit behavior with a HIGH output result.

Step-by-Step Solution:

Verification / Alternative check:

Create a brief truth table for NAND. You will find that any row containing a 0 produces Y = 1, confirming the observation made in the problem statement.

Why Other Options Are Wrong:

• AND would output LOW when any input is LOW.
• NOR outputs HIGH only when all inputs are LOW, not merely one.
• OR outputs LOW only when all inputs are LOW; otherwise it is HIGH but does not match the inhibit description.
• XOR depends on odd parity of HIGH inputs, not a general inhibit behavior.

Common Pitfalls:

• Confusing NAND with NOR. Remember: NAND needs all inputs HIGH to go LOW.

Final Answer:

NAND