Re: ZIPGS 2-pin Crystal

[andrew.webber2@btinternet.com (Andrew Webber)]

andrew.webber2@btinternet.com (Andrew Webber) wrote in message news:<6b297ed0.0206192258.20e0f494@posting.google.com>...
> Wayne Stewart <waynes@intergate.ca> wrote in message news:<3D05573B.D5BEB89E@intergate.ca>...
> > Andrew Webber wrote:
> > 
> >  
> > > I just snipped the crystal and put in a 32Mhz oscillator. All worked
> > > ok :-).
> > > 
> > > I then put in a 40Mhz oscillator and the system did not start, just a
> > > single character appear on screen. I still have to change the SRAMs so
> > > I think thats the cause.
> > > 
> > > Does that sound right?
> > 
> > Yep, changing to faster SRAM should allow you to get up to around 12mhz.
> > After that you may, depending on your luck have to change the 74F00 to a 
> > 74HC00.
> > 
> > 	Wayne
> 
> 
> Thought I would update you on my ZIPGS 1.01 upgrade...
> 
> I bought 4 converters for SRAM sockets to allow a set of skinny
> cache/tag chips to go in (I am not keen to cut and resolder the
> sockets). I purchased 4 x 15ns Cypress 32kx8 Cache Chips
> (CY7C19915VC)from RS components in the UK (�1.19 each). The converter
> sockets I had to sand down the edges to get them all to fit in. That
> was fun (not).
> 
> Powered up my system (ROM01, Stock PSU, 1MB Ram, SCSI Card) and all
> works fine as a 8/64 system with a 65c816-14 chip and a 32Mhz
> oscillator.
> 
> I decided to put a 40Mhz Oscillator and the system will hang in after
> a about 5 - 10 minutes on the Out of this world demo at the same
> location. Any ideas why that is? I then tried the 50Mhz oscillator and
> the system starts to put GS/OS then bombs out.
> 
> 
> I moved the card to my Rom03(Vulcan 40, CCFA Card,5MB Ram) GS and all
> seems to work fine (demo was running for over 2 Hours) with a 40Mhz
> Oscillator.
> 
> I then decided to put a (Still ROM03) a 50Mhz Oscillator in and as
> soon as I boot the system I get a Fatal 911 error. Any ideas if this
> is ZIP related or Motherboard not being able to cope with the speed?
> If i take the 50Mhz chip out and put in a 40Mhz it works. I have read
> some posts that this could be the ADB port?
> 
> I appreciate your help
> 
> Andrew


I tried another 50Mhz oscillator and this time it at least booted, but
was not very stable. I droped the cache down to 32K and all seems
(cross fingers) ok. Made it 12.5 Mhz Yippie!

Andrew