Re: RAM for Zip GS

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <252112862.23698675@adbbs.antioch.edu>,
John L. Graham <John_L._Graham@adbbs.antioch.edu> wrote:
> I recently bought a 7/8 Zip GS from Alltech and I'd like to upgrade
> the cache RAM. I have four RAM chips that came with my 10/64 Zip GS I
> bought second-hand. [snip]
> 
> Two of them are labeled...
> 
>      JAPAN
>      81C78A-45P
>      8810 X08

I don't know what size this one is (probably 8KB), but the speed is 45
ns.  That should be fast enough for 10 MHz.

> another is labeled...
> 
>      MOSEL
>      MS6264AL-70PC
>      8910 K

An 8KB static RAM chip, speed 70 ns.

> and the last is labeled...
> 
>      622106
>      M5M5165P-70

That's almost certainly "MSM", not "M5M".  Also not clear on the size,
but I'd guess 8KB again.  It is also 70 ns.

Install the faster chips in the "TAG" sockets, and the slower ones in
the "DATA" sockets.  (It doesn't really matter in this case.)

You will only be able to increase the cache size to 16K, but that
should make a noticeable difference to the speed.

> Also, I assume the DIP switches have to be reset for the new RAM chips.

Yes.  They are documented in the manual which was originally
distributed with the ZIP, but the later manual removed all
documentation on the switches.

The ones you need to change are:

SW1-7  SW1-8    Cache size
ON     ON       8K
ON     OFF      16K         <------------ this is the one you want
OFF    ON       32K
OFF    OFF      64K

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand