Re: Problem with 14MHz 65816 chip in ZipGS

[waynes@intergate.ca (Wayne Stewart)]

Rodney Hester wrote 
> I currently have a version 1.02 ZipGS unit with a soldered 9MHz oscillator.
> It came with the standard 10MHz 65c816 chip on-board.  I tried to replace it
> with a 14MHz part from WDC (with the understanding it would still only run
> at 9MHz - it was just the first step of an upgrade procedure), and with the
> 14MHz chip installed, the board repeatedly crashes into the monitor within a
> few minutes.  The 10MHz chip performs flawlessly, even after 4 hours of
> stress-testing followed by 12 hours of burn-in testing.
> 
> Am I looking at a static-damaged chip or the like here?  The chip has some
> age on it, and to the best of my knowledge was never previously tested or
> used - just kept in storage.  If it really is defunct, who still sells these
> things?

I believe there was an earlier 14mhz chip and another 14mhz one after Sanyo 
redesigned WDCs dies. I think the earlier one was an experimentors chip, not 
a production model and people had varying luck with it. The Sanyo version had 
a much heavier WDC logo on it.

If you're going to try for higher speed, I'd likely socket the oscillator and 
see how fast you can go. There's a possibility you may not need a faster 65816. 
The ZipGS is a lot more tollerant of overclocking the processor than the  
TransWarpGS was. I'm using an 8mhz 65816 in a ZipGS running at 15mhz. I did 
try a 14mhz 65816 but in my case there was no noticeable difference. Course 
I did need faster cache  and a 74HC00
 

	Wayne