Difficulty: Easy
Correct Answer: Incorrect
Explanation:
Introduction / Context:This item distinguishes a full adder from a half adder. A full adder is the standard 1-bit building block used to construct multi-bit adders because it accepts a carry in (Cin) and produces a carry out (Cout).
Given Data / Assumptions:
Concept / Approach:A half adder adds two bits (A, B) but has no Cin. A full adder adds A, B, and Cin, producing Sum and Cout. Multi-bit adders cascade full adders by wiring each stage’s Cout to the next stage’s Cin, enabling n-bit arithmetic.
Step-by-Step Solution:
Identify the device in question: “full adder.”Recall its interfaces: inputs A, B, Cin; outputs Sum, Cout.Compare with the claim: “need not have carry in/out” → contradicts definition → evaluation is “Incorrect.”Verification / Alternative check:Common logic equations: Sum = A xor B xor Cin; Cout = majority(A, B, Cin). These require Cin and produce Cout.
Why Other Options Are Wrong:
Correct: Would match a half adder, not a full adder.Only correct for ripple chains: Ripple needs Cin/Cout explicitly.Ambiguous/Implementation-dependent: The definition is standard, not optional.Common Pitfalls:Confusing half adders with full adders.
Final Answer:Incorrect
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