Abstract: Pseudorandom Boundary-Scan testing of a interconnects within a system (10) is accomplished by first generating a pseudorandom pattern and then filtering the pattern before application to the system to modify values within each pattern that could cause a signal conflict. Each response generated by the system upon application to the system is also filtered to mask non-deterministic values with the response. The filtered response is compared to a set of signatures representing a fault-free condition to detect faults within the system.

Abstract: Verification of test information transmitted across an 1149.1 backplane test bus between a circuit board (12.sub.1) and a test master (14) is accomplished by having both the test master and the circuit board compute a cheek code for each block of information that is transmitted by, or received at, the board. During intervals other than one of the active Boundary-Scan states, the test master (14) acquires the check codes produced at the circuit board (12.sub.1) and compares them to the corresponding codes generated by the tests master. Any difference between the corresponding codes generated by the test master and the circuit board signifies a transmission error.