Re: ZIPGS

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

In article <C112094235349.2@ocean-side.ecore.fnet.org>,
 <Spaceman_Spiff@ocean-side.ecore.fnet.org> wrote:
> 
> What is the bottom line with upgrading the ZIPGS to faster speeds?  Could I
> just replace the Oscillator from 32MHZ (7MHZ GS speed) to 40MHZ (10MHZ GS
> speed)?  Will this modifacation work?

Actually, 32 MHz results in an 8 MHz ZIP, not 7 MHz (that would be a 28
MHz crystal or oscillator).

Replacing the oscillator is only one of the steps that may be required.

The processor is rated to run at a specified speed, and no higher.
You may be able to get it to work a little faster than its rated speed
(e.g. my 8 MHz ZIP had a 7 MHz processor, but it didn't work reliably
after a year or two).  You can also increase the voltage supplied to
the CPU to make it run faster (there is some optional circuitry on the
card to allow this).

A better option is to replace the processor with one rated to run at a
higher speed.  A 65816 rated at 14 MHz is about US$20.

The second problem is the RAM chips, which may need to be replaced
with higher speed ones.  60 ns RAMs are sufficient for 8 MHz (I've seen
a 9 MHz ZIP which uses 70 ns, but they were probably hand picked and
tested by ZIP).  You should use 45 ns or thereabouts for 10 MHz.

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