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Codiode/Problems/Combinational Logic

Debug Full Adder Carry Logic

MediumLogic CircuitDebug

A full adder computes the arithmetic sum of three 1-bit inputs and produces a sum and a carry out.

Expected behavior:

| A | B | Cin | Sum | Cout | |-----|-----|-------|-------|--------| | 0 | 0 | 0 | 0 | 0 | | 0 | 0 | 1 | 1 | 0 | | 0 | 1 | 0 | 1 | 0 | | 0 | 1 | 1 | 0 | 1 | | 1 | 0 | 0 | 1 | 0 | | 1 | 0 | 1 | 0 | 1 | | 1 | 1 | 0 | 0 | 1 | | 1 | 1 | 1 | 1 | 1 |

Simulation shows Cout = 0 for inputs A=1, B=1, Cin=1. The carry output is incorrect for this specific maximum input case. Inspect the circuit and correct the fault.

Constraints

  • Do not modify the sum logic pathways
  • Replace only the faulty logic gate
  • Do not add any new wires or components

Topics

arithmeticadderdebug

Solve this problem

Place the gates, wire them up and watch the signals settle. Every submission runs on the same simulation engine that grades it.

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