Re: Technical Information for GS Accelerators

["Sheldon Simms" <sheldonsimms@yahoo.com>]

On Thu, 15 May 2003 04:44:05 +0000, Rubywand wrote:

> vector writes ...
>> 
>> Hrm.  Where can I find nicely detailed technical data about the
>> Transwarp GS and/or Zip GS, up to and including schematics?  Is there
>> a source for that sort of thing?  I'd also appreciate information on
>> the general design of third-party hardware cpu accelerators, even if
>> not Apple II specific.  I'm sort of doing a research project.
> 
>      I've never seen a schematic or highly detailed description for either the
> Transwarp GS or ZipGS. There is some information-- mostly related to speeding
> up boards-- in the FAQs at http://home.swbell.net/rubywand/Csa2ACCEL.html .

Suddenly, I'd also like a Zip GS schematic, but since I don't have one
maybe someone here can help me out...

I have had a Zip 7/32 for years. Just a couple of days ago I decided to
attempt to upgrade it. I concentrated on the speed first, figuring that
I could easily increase the cache after I got the frequency up as high
as possible. By changing a 50Mhz oscillator and faster (15ns/25ns) SRAMs
I got it up to 12.5 Mhz quite easily. I wanted to try to get it going
faster so I wanted to replace the 74F00 with a 75HC00 as described in
various Zip upgrade guides on the net.

Unfortunately, at this point I accidently removed two traces on the board.
One seemed to go from pin 1 to pin 14 of the 74F00 and the other seemed to
go from pin 14 to pin 12 of the 74F00. I have attempted to repair this
problem by installing a the 74HC00 in a socket and tacking on jumper wires
between the appropriate pins to replace the traces I lifted. After doing
this I was once again running at 12.5Mhz with 32kb cache.

After I tried unsuccessfully to increase to 16Mhz. (Don't have any
oscillators between 50 and 64 Mhz at the moment) I decided to add another
32kb cache. Adding it was easy but it doesn't work. If I set the dip
switches for 64kb my IIgs doesn't boot.

So my question is, does anyone know if my problem with the traces around
the 74F00 might be the cause of the problem with 64kb cache?

-Sheldon