a boundary scan test system including a transmitter and a receiver . the system performs dc and ac boundary scan testing of the interconnections between devices . the system addresses fault masking that can occur during testing . of concern are ac coupled interconnections while providing ieee 1149 . 1 dc test compatibility . the test receiver includes an input test buffer and an interface mechanism . the input test buffer has a built - in null detection capability . the interface mechanism includes a technology mapper , one or more detectors , and an integrator . the receiver provides at least partial , if not complete , coverage for at least one of five fault syndromes that can result from single defect conditions in the system .