[vcf-midatlantic] IBM FSU Static RAM Board...for S-100?!

Connor Krukosky connork at connorsdomain.com
Fri Jan 22 00:57:51 EST 2016

I have three of the FSU ram cards for IBM PC, they are quite odd indeed.
That S-100 board though is the most interesting use of them I have ever 

I'd think the only way to get reliable replacements would be to make a 
small PCB with a small surface-mount S-RAM chip on it to break out to 
the original header.
And if you feel you must make it look original as possible you could pop 
the cap off the old chip and stick it over the new board.
I'd think this would be the only reasonable way to get replacements.

I will be checking my ram boards shortly since I just picked up an IBM 
PC that should be in good working condition.
If there are any failures of the FSU modules that's the route I will 
probably go.

Sadly you obviously can't use the ISA card's chips to replace the ones 
in the S-100 board since they were made about 10 years apart according 
to size and chip date codes.
The FSU modules on the ISA card should be 64k x 9 (maybe only 64k x 8)?
The part number being 6119927.

-Connor K

On 1/21/2016 10:17 AM, william degnan via vcf-midatlantic wrote:
> Here is a photo of an early IBM bus RAM card, same FSU RAM.  This is a 256K
> RAM card for the IBM PC.
> http://vintagecomputer.net/vcf8/Degnan_exhibit_IBM-256K_memory.jpg
> On Thu, Jan 21, 2016 at 10:02 AM, Systems Glitch via vcf-midatlantic <
> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>> This has to be one of the most unexpected S-100 boards I've acquired. The
>> seller says this was created due to the need for denser RAM boards for
>> IMSAI 8080's at IBM's Advanced Systems Development Lab in Los Gatos,
>> California. Apparently FSU RAM was the densest static RAM available at the
>> time, and of course they had access to it, being IBMers. Extra boards were
>> produced for engineers with S-100 machines at home. I wrote up what I know
>> about the boards here:
>> http://www.glitchwrks.com/2016/01/20/fsu-ram
>> Fortunately they came with a copy of the 3-page manual and a (very faded)
>> blueprint copy of the schematic. I've digitized both and made them
>> available. I've tested one of the boards so far, which works fine with my
>> IMSAI 8080 and a 2 MHz 8080 CPU board. I'd be interested to hear if anyone
>> else knows anything about these, or has one, or has spare FSU RAM modules
>> they'd be interested in parting with.
>> Thanks,
>> Jonathan

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