Launch-on-shift (LOS)
Beginner
A way to start a speed test using the very last step of loading the pattern.
Novice
Also called skewed-load. The last shift tick of loading creates the change (the second pattern is the first one moved along by one bit). Scan enable then switches off and one fast tick catches the result.
Expert
Higher transition coverage, but scan enable must fall within one functional clock period chip-wide, and launch states that normal operation never reaches can fail good parts.
Explained in Design for test (Design Flow).
See also: Launch-on-capture (LOC), Scan enable.