Re: Overclockinga ZipGSX, advice please

["PZ" <skierpaul@yahoo.com>]

Hi Jamie.

You've definately hit a wall with the cache ram.  You'll want to
scavenge some 32k x 8 srams off of some old Socket 7 motherboards.  -20
(20ns) and -25 (25ns) chips are very common and -15 (15ns) are more
rare but still not to hard to find.  Install skinny sockets (machine
pin prefferably), since the fastest you'll find a 600mil SRAM is 45ns.
(Sony used to make 25ns wide DIPs, but GFL finding those)  BTW, some
brands work better than others, so get a variety if you can.

I'm assuming you already have a socket installed for your xtals, so
you're good there.

You'll want to install machine pin sockets for the 2 TTL logic chips on
the board.  Replace with 74HCxx or 74AHCxx.  You can start out with
just replacing the 74F00 and experiment on from there.  (The HC is
slower than the F but offers a cleaner CMOS output.)

A nice clean powersupply like the one Henry sells and a ROM 3 certainly
help, however if you can make it stable on a ROM 1, then you'll never
have problems on a cleaner system.  If it takes a cleaner system to
make it run faster, you'll still have occasional crashes.

Thats about it.  Have at it.  Have fun.  Good luck!
- Paul

macdog wrote:
> I am trying to overclock a ZipGSX I just picked up.  I have it running
> at 10 Mhz, rock solid.  When I got it, it had no oscillator or cable,
> and it had an 8 Mhz WD 65816 PLCC chip which I replaced with a 14 Mhz
> version.  I successfully used 7, 8, and 10 Mhz (27, 32, 40 Mhz)
> oscillators so far.  So far, when I have attempted to install faster
> oscillators, the GS has not booted.  Not even a checkerboard
> screen....It just acts dead.  I note that the ram cache has chips that
> end with a 7.  I assume them to be 70 ns.  In order to bump up the
> speed even more, I think I heard that I need to speed up the Cache ram
> to something faster.  Does anyone have any experience doing this kind
> of thing?  I would appreciate any advice on this endeavor.  Thanks.
> Macdog, aka Jamie Steffens.