It is shown that for a two-level irredundant single/multiple output combinational circuit, the checkpoints consist of all primary inputs without fanout, and all fanout branches in the circuit. Any test set that detects all single stuck faults on these checkpoints will also detect all single stuck faults in the circuit.
This work was supported by National Science Council, R.O.C., through the contract: NSC79-0404-E009-22 and NSC80-0404-E-216-01.