Re: Some questions about a2 upgrading

[david@uow.edu.au (David Wilson)]

"Byron Q. Desnoyers Winmill" <byron@asimov.ab.hsia.telus.net> writes:

>**** **** <***@***.com> wrote:
>> Others have mentioned ram expansion cards, and which is preferable to
>> the other. Is this an area for improvement? It was said that both cards were
>> 1 meg... is there any major reason why this couldn't be 4 megs, or more?
>> What would be the preferred socket for these? Would going with a 72pin simm
>> make it less desirable for some?

>72 pin SIMMs could be an issue.  It is probably best to stick with chip RAM
>and 30 pin SIMMs since they were both common in the past, and the machines
>that they were used in were dragged out of service years ago.  With the 72
>pin variety, you are still fighting with various 486/Pentium and Macintosh
>users for the memory -- so the supply isn't really what it should be.

The other advantage of chips & 30pin SIMMs is that the A2 series need 8bit
RAM while a 72pin SIMM is 32bits wide amking it less easy to interface.

The //gs was designed to refresh 256Kb and 1Mb chips, in one to four banks.
Thus a 4MB card is the standard maximum. If you work at it you can make
an 8MB card but it may not work for DMA.
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia