culhane@vis.toronto.edu (Sean Culhane) (11/28/90)
HELP!! I just received 2MB of RAM chips for my 2091 controller, and the
RAMTest tells me that some of the RAM is bad. BUT it appears to be a problem
with the 2091, *not* the chips. Here's the scoop. Any and all help is
welcome.
Chips are Fujitsu (sp?) part #MB81C4256-80P, with the additional markings
on the chips: 9040 F99ZBC
I've set the jumper to the 2MB position.
Avail says 3MB are present (so does ClockDJ)
When I run the RAMTest program supplied with the 2091 controller. (BTW,
I never received any written docs for my 2091, so maybe the solution
lies in such a document??) It checks the first 1MB quite quickly
(~40sec to check 200000 to 2ff000), then takes somewhat longer (~65sec)
to check the second MB (300000 to 3ff000). Then I get:
RAM fails data test:
Total failure on U22 (check pins 3, 4, 10, 17, 20)
Total failure on U23 (check pins 3, 4, 10, 17, 20)
Total failure on U24 (check pins 3, 4, 10, 17, 20)
Total failure on U25 (check pins 3, 4, 10, 17, 20)
Total failure on U26 (check pins 3, 4, 10, 17, 20)
Total failure on U27 (check pins 3, 4, 10, 17, 20)
Total failure on U28 (check pins 3, 4, 10, 17, 20)
Total failure on U29 (check pins 3, 4, 10, 17, 20)
RAM passes unique address test
RAM passes interbank addressing test
And it draws a red 'X' through the left-most 2 rows of chips (that's
half of them!)
It seemed fishy that exactly half the chips were bad (and all together),
so I swapped a few 'good' ones with the 'bad' ones (according to RAMTest)
And got the EXACT SAME RESULT!! (This tells me the chips are OK, but not
my 2091 :-( )
I thought that maybe this RAMTest is just super-sensitive, and the RAM
is OK to use anyway, so I pull a HUGE file into an editor, and watch
the fast memory count drop. Sure enough, as soon as the second MB is
accessed, GURU!! (00000003.0021FF90) Later, I got 00000003.00213BF0
in a similar way when using up all of the first MB or RAM.
All you 2091 experts out there, ***PLEASE*** __HELP__ ME!!!
Thanks in advance.
Sean.
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(_)>(_) sean. (culhane@vis.toronto.edu)