Inequality detection: The ________ logic function produces a HIGH output whenever its two inputs are unequal (different).
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Aexclusive-AND
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Bexclusive-NOR
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Cexclusive-OR
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Dinexclusive-OR
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ENOR
Answer
Correct Answer: exclusive-OR
Explanation
Introduction / Context:Detecting whether two signals differ is fundamental in adders, parity generators, and error checking. The gate that signals “different” with a HIGH output is the XOR (exclusive-OR).
Given Data / Assumptions:
- Two-input standard logic functions.
- Positive logic convention.
Concept / Approach:XOR outputs 1 when inputs are different (01 or 10) and 0 when they are equal (00 or 11). Its complement, XNOR, signals equality. Terms like “exclusive-AND” or “inexclusive-OR” are not standard logic functions.
Step-by-Step Solution:
Recall XOR identity: F = A′B + AB′.Evaluate for all four input pairs; F = 1 only for 01 and 10.Therefore, XOR detects inequality directly.Choose “exclusive-OR.”Verification / Alternative check:Implement using half-adder sum output; the sum bit equals A XOR B, which is 1 when inputs differ, further confirming behavior.
Why Other Options Are Wrong:
- exclusive-NOR: Equality detection (opposite of required).
- exclusive-AND / inexclusive-OR: Nonstandard or meaningless in common logic nomenclature.
- NOR: 1 only when both inputs 0; not an inequality detector.
Common Pitfalls:Swapping XOR and XNOR meanings; assuming NOR/AND derivatives can serve as direct inequality detectors without additional logic.
Final Answer:exclusive-OR