This puts the tester inside the chip. Logic BIST (LBIST) and Memory BIST (MBIST) allow the device to test itself at full clock speed, which is essential for detecting "at-speed" defects that slow testers might miss.
At 3 AM on Thursday, they had it: a sequence of 47 test vectors. It looked like gibberish—a cascade of 1s and 0s—but it was a skeleton key.
