Abstract: A method of and an apparatus for counting is disclosed. The counter includes a generator of cross-tie, Bloch-line pairs and a shift register of N stages or memory cells along which the cross-tie, Bloch-line pairs are propagated or replicated into a detector. The method includes coupling a series of bipolar push-nucleate replicate signals, each one of which produces a cross-tie, Bloch-line pair in the adjacent downstream memory cell along the shift register. When the shift register is filled, a cross-tie will appear in the detector. This provides an output signal indicating that the N memory cells have been filled by the N replicate signals.

Abstract: A self-test monitor and diagnostic apparatus which includes a test step counter, an error comparator apparatus, which may be a memory device loaded so as to predict the proper state of each of the lines to be monitored at each test step and which functions to detect any difference between what should be occurring at that test step and what is, in fact, occurring on the monitored line, and an error localization network which translates the detected errors into a displayable code for maintenance isolation.