Likewise the input could be tied to a logical 0 to model the behavior of a defective circuit that cannot switch its output pin.
Also, redundant circuits cannot be tested using this model, since by design there is no change in any output as a result of a single fault.
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 model also fails to detect bridging faults between adjacent signal lines, occurring in pins that drive bus connections and array structures.
Nevertheless, the concept of single stuck-at faults is widely used, and with some additional tests has allowed industry to ship an acceptable low number of bad circuits.