McCullar's Law: "All test equipment will lie to you at some time or
another."
Atari's built-in self tests are usually pretty good, but there are always
exceptions. Equipment that tests RAMs in stand-alone applications can vary
in quality. I have had RAM chips that pass these PC-based OK, yet still
fail when plugged into an _Asteroids_ or similar board.
I'm not an expert in this matter, but my opinion is that the test equipment
may not be putting enough of a load on the RAM chip. The RAM may be damaged
just enough so that it can produce enough current in test, but when placed
on the motherboard it's pushed hard enough to fail.
I like to use an X-Y component tester on these RAM chips because sometimes
you see failures that just won't appear any other way. One I/O line may be
leaking, though not shorted. Or its 5-volt line may be leaking, too.
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Received on Sat Aug 24 11:00:12 2002
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