| ??? 09/25/10 08:12 Read: times |
#178706 - Areas of Doubt and Uncertainty Responding to: ???'s previous message |
Neil Kurzman said:
try every pattern on the chip under test How long would that take?! How many combinations of input, output, clock, etc are there for such a "brute-force" attack on even a 14-pin chip...?! And that's before you even think of stored state... compare it to a know good one. I wonder what the possibility is that a faulty chip could "look like" some other chip when exercised like this? Or choose the chip and run its truth table on the chip. I think that's going to be far more practical - although, again, a simple truth table is not sufficient to describe all logic chips. It can not test Micros. They do not have truth tables. Unless the micro is programmed to work with the tester. I guess you could say that the "program" forms part of the input to the truth table...? ;-) |
