Magnitude comparator fundamentals – identify the standard trio of comparison outputs a digital magnitude comparator asserts when comparing two binary numbers A and B.

Difficulty: Easy

Correct Answer: A < B, A = B, and A > B

Explanation:


Introduction / Context:
A magnitude comparator is an MSI logic device that compares two numbers and reports their relative ordering. Understanding its outputs is essential for tasks such as sorting networks, range checking, and multiword comparisons. This question asks you to recall the canonical output set that captures less-than, equality, and greater-than relationships.


Given Data / Assumptions:

  • Inputs: two unsigned binary numbers A and B of equal width.
  • Goal: produce ordering signals indicating A < B, A = B, or A > B.
  • Cascade pins may exist to chain multiple comparator ICs for wider words.


Concept / Approach:
The complete ordering relationship between two values can be represented by three mutually exclusive signals. A proper magnitude comparator asserts exactly one of these at a time. Many families (for example, 74xx85-type) implement these outputs and include cascade inputs so higher-order results override lower-order ties when expanding to larger bit widths.


Step-by-Step Solution:

Compare the most significant bit first; if unequal, decide A > B or A < B.If MSBs match, proceed to next bits until a difference is found.If all bits match, assert the equality output.Expose the result on A<B, A=B, A>B pins to drive control logic.


Verification / Alternative check:
Review a standard comparator truth table: for any input pair, only one of the three outputs becomes active. Cascading rules ensure that a decision at a higher block suppresses conflicting indications at lower blocks.


Why Other Options Are Wrong:
“Sum/difference/carry” and “Cin/Cout/Sum” are adder-related. “A=B, A+B, carry” mixes comparison with arithmetic. “Overflow/zero/negative” are ALU status flags, not the basic comparator outputs.


Common Pitfalls:
Confusing ALU flags with comparator outputs; forgetting signed versus unsigned interpretations (magnitude comparators are typically unsigned).


Final Answer:
A < B, A = B, and A > B

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