Shift and capture
Beginner
The two steps of a scan test: slide a pattern into the chip’s memory cells, then let the chip take one step and catch the result.
Novice
Shift: with scan enable on, clock the chains once per flip-flop in the chain to load a pattern (and push out the previous result). Capture: with scan enable off, give one normal clock tick (two for timing tests) so every flip-flop stores what the logic computed.
Expert
Shift is slow and long (one cycle per bit of the longest chain); capture is a few cycles and may run at full speed. Unloading pattern overlaps loading pattern . Shift power and capture power are separate limits.