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Codiode/Problems/Combinational Logic

Debug Combinational: Parity Generator Gate Swap

MediumLogic CircuitDebug

Error detection systems rely on parity generators to append a validation bit to transmitted data. An 8-bit even parity generator computes a single parity bit P that makes the total number of high bits in the overall 9-bit word even. The output P must be the XOR sum of inputs D0 through D7.

Expected behavior:

The output P must be 1 when the input word contains an odd number of 1s, and 0 when it contains an even number of 1s.

Simulation shows P = 1 for input D0=0, D1=0, D2=0, D3=0, D4=0, D5=0, D6=0, D7=0. The parity output is incorrect across multiple test cases, effectively producing odd parity instead of even parity. Inspect the circuit and correct the fault.

Constraints

  • Modify only the faulty component.
  • Do not add any new input or output pins.
  • Maintain the existing tree structure of the logic.

Topics

DebugFault Testing and VerificationParity

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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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