>What is the right way to check for defective RAM chips?
The best thing to do here is check to see if the RAM will reliably save
values written to it over time and with activity on the chip. Looking at
the data bus alone will be tough because the bus can be fine-- you're really
interested in the actual bits that are on the chip.
The RAM test that a game board runs is a pretty good way to find a bad RAM.
They usually do some bit patterns and whatnot at least. RAMs are best
tested at full speed in the system they're used on-- removing and trying
them on a cheap device tester often won't work. Also, RAMs can have
peculiar failures. They can have sensitivity to patterns or certain areas
being hit-- often sequential reads/writes will be fine but random
read/writes will fail (and vice-versa).
If you don't have a lot of time or tools, sometimes it's easiest to just
pull the chip and plug in a replacement-- or swap it with another one on the
board and see if the problem follows the chip.
-Clay
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Received on Tue Apr 25 00:32:35 2000
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