ENHANCING BOARD FUNCTIONAL SELF-TEST BY CONCURRENT SAMPLING

Board test using functioiial self-test code can be augmented by concurrently sampling signals at chip boundaries, compressing this data, and verifying its signature in-line in the code. This is a general method to enhance board test and diagnosis, po1,erXtidy adding every chip J/O pin as an observation point that is observed frequently and coupled to the self-test. Tests continue to execute at the normal board operating speed. This combination of fnnctional and strudural testing offers improved effectiveness over functional testing alone.