model assumes that only one input on one gate will be faulty at a time, assuming that if more are faulty, a test that can detect any single fault, should easily find multiple faults.

To use this fault model, each input pin on each gate in turn, is assumed to be grounded, and a test vector is developed to indicate the circuit is faulty. The test vector is a collection of bits to apply to the circuit's inputs, and a collection of bits expected at the circuit's output. If the gate pin under consideration is grounded, and this test vector