Re: SIMMS for IIgs

[a_specto@alcor.concordia.ca (Mitchell Spector)]

"william strutts" <wrstrutts1@nospam.home.com> wrote:

>"Mitchell Spector" <a_specto@alcor.concordia.ca> wrote in message
>
>>     Of existing IIgs memory cards that support SIMMs, they'd have to
>> fall under this set of guidelines: Either 256K or 1MB SIMMs, 8 or 9
>> chips on the PCB (meaning 1 bit chips--parity or non-parity), 30-pin
>> (8-bit), and at least 150ns or faster. CAS before RAS refreshing may
>> not be an issue, I've never heard of SIMMs which use the reverse
>> order.
>>
>>     The other thing to watch for is the card's configuration. Often you
>> have to set DIP switches or jumpers to tell the card which sockets
>> are populated. If your not fully populating the card, you may have to
>> plug them in a certain order. Finally most cards only accept one type
>> of SIMM or the other (all 256K or all 1MB, not a mix).
>
>It has four simm slots and a dip switch which turns each bank
>on or off.

    Are you sure the DIP switches work that way? It seems obvious that
they would, but some cards are configured in odd ways.

>They have to be installed in pairs I think.

    It should technically work with one SIMM at a time (they're 8-bit, and
externally that is what the 65C816 is) though generally it depends on 
the card itself and how it addresses each bank rather than trying to 
follow that other rule.

>I have two megs of simms that came with the card and they work fine.
>However, if I replace them with the new RAM, the machine
>locks up on booting GS/OS.  The loading bar keeps moving
>but the disk drive freezes.  I used a mix of the two types of
>RAM in different banks and it won't load either.  I didn't try
>putting all four of the new memory in and see if it works. It
>is possible that one of them is bad.  I put the original memory
>back in and it works fine.  The only difference I can see is
>that the original RAM is taller and has gold contacts and the
>new memory is low-profile and has silver contacts.  Would
>this be a problem???

    That shouldn't make a difference. Have you tested these SIMMs in
another machine to verify they work? Better yet, have you checked
that they actually _are_ 1MB SIMMs? (check the part numbers on the
chips themselves).

Mitchell Spector
a_specto@alcor.concordia.ca