Re: IIgs problem...

[oaaland@aol.com (O Aaland)]

>More on the IIgs memory problem and error $0682...
>
>Moved the chips around again, now the card is laid out so that the top row
>is 16 150ns chips (8 soldered on) and the bottom is 16 120ns chips.
>I just don't have another 16 150ns chips to put there.
>Anyway, here's the thing. Startup without card in...computer works fine.
>Startup with card with no jumpers (only first 8 chips in upper bank used,
>right?)...works fine.
>Startup with upper jumper on (upper bank used, right?)...works fine
>Startup with bottom jumper on (bottom bank used, right?)...works fine
>Put both jumpers on, and wham. There's the errors and crashing.
>So, I'm guessing that it's not the chips themselves, but an interaction
>between 150ns and 120ns RAM? Or am I missing something?


The GS memory card is laid out so that with no jumpers it only uses the
soldered on memory. When the rest of the top row is filled in the BOTTOM jumper
is used. This row must be filled and the correct jumper in place before filling
the bottom row. The bottom row must be completely filled in order to be used,
eight chip configuration is not supported. With the bottom row filled the TOP
jumper must also be used.

In think your problem is in the lower bank. When you have just the TOP jumper
in place you are only using the first bank on the top. As long as you can
consistantly cause crashes with the memory active you may be able to determione
a bad chip by ussing the BOTTOM jumper only. Since it works now with only the
bottom jumper start by swapping one of the bottom banks for the top one. If it
still works then swap in the other bottom bank. When you get it to crash then
swap four of the chips with four of the known good one that were originally in
the upper bank. If it still crashes change two more chips. If it still crashes
then chang one of the remaining two chips. It may take a few times since you
may have more than one bad chip.

Owen