A test system for functionally testing a microprocessor-based assembly, and apparatus for testing logic circuitry

摘要

AA microprocessor-based test system for functionally testing and troubleshooting microprocessor-based systems is connected in place of the microprocessor circuit of the unit 18 being tested (UUT). The test system includes a microprocessor circuit 42 which is supplied with the UUT clock signal and is the same type of microprocessor circuit as is utilized by the UUT 18. The test system periodically switches this microprocessor 42 into signal communication with the UUT 18 for a single UUT bus cycle to perform UUT read or write operations. During remaining time periods, the test system microprocessor circuit 42 is in signal communication with the remaining portion of the test system to analyze data obtained from the UUT bus during the previous UUT write or read operation and to establish the signals to be used in the next UUT write or read operation. Various test sequences are provided for testing the UUT bus, RAM, ROM, and write-responsive I/0 registers 26, 28 and 30.