Abstract: A system and method for diagnosing the faults of an electronic device by running a series of tests, identifying the tests where the electronic device failed, without having to check the results of each test, storing information generated during only the tests where the electronic device failed, and using the information to diagnose the faults in the electronic device. The test results are accumulated into a Multiple Input Shift Register (MISR) which need not be examined after each test to determine which tests the device failed. The problem of a failure during one test manifesting into the MISR during subsequent tests is handled by predicting the effect of the failure on the MISR during subsequent tests.

Abstract: Apparatus for applying for a plurality of test cycles data specifying a plurality of test conditions to a multiple pin electronic circuit. A random access memory includes at a plurality of higher order addresses a complete data field for a plurality of test cycles. Some of said data fields include an operational code indicating that a minority of data bits in a field are to change in a consecutive number of following test cycles. A hold register is connected to receive each addressed row of test data from the memory. The higher order addresses of a memory addressed to produce complete data fields in the hold register. An operational code will be decoded to indicate a number of subsequent consecutive test cycles where a minority of data in the hold register are to be changed. The lower order addresses of the memory are subsequently addressed for a number of consecutive test cycles indicated by the operational code.