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Codiode/Problems/Combinational Logic

Shared Gate Fault Propagation

HardLogic CircuitBuild

Hardware debugging often reveals that modifying a shared logic cone introduces functional bugs across multiple downstream paths. Multi-output synthesis relies on shared gates to save area, but a single stuck-at fault propagates to all connected outputs.

Implement a dual-output combinational circuit alongside its fault-injected equivalent. The base shared node is S = A & B. The primary outputs are F1 = S | C and F2 = S ^ C. The fault outputs F1_err and F2_err must represent the exact logic behavior if the shared node S is permanently tied to 1.

| A | B | C | F1 | F2 | F1_err | F2_err | |-----|-----|-----|------|------|----------|----------| | 0 | 0 | 0 | 0 | 0 | 1 | 1 | | 0 | 0 | 1 | 1 | 1 | 1 | 0 | | 0 | 1 | 0 | 0 | 0 | 1 | 1 | | 0 | 1 | 1 | 1 | 1 | 1 | 0 | | 1 | 0 | 0 | 0 | 0 | 1 | 1 | | 1 | 0 | 1 | 1 | 1 | 1 | 0 | | 1 | 1 | 0 | 1 | 1 | 1 | 1 | | 1 | 1 | 1 | 1 | 0 | 1 | 0 |

Constraints

  • Implement strictly combinational logic.
  • Drive all four output ports using standard logic gates.
  • Do not use high-level arithmetic blocks or multiplexers.

Topics

gate-leveldebuggingfaults

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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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