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GATE 2014 EC (EC3) – Question 52

Digital Circuits · Combinatorial Circuits · 2 marks · Multiple choice

With inputs X,Y, difference D = X − Y and borrow B, which diagram implements a half-subtractor?

Diagram for GATE 2014 EC (EC3) question 52
  1. Diagram A
  2. Diagram B
  3. Diagram C
  4. Diagram D

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Show answer and explanation

Correct answer: (A) Diagram A

Explanation

A half-subtractor for X−Y requires difference D=X XOR Y and borrow B=X̄Y. In **A**, selecting Y or Ȳ with X produces the XOR difference, while selecting Y or0with X produces X̄Y. Both outputs therefore match the required truth table.