Snippets from a
July 1993 FAQ ("mini-FAQ: upgrading TransWarp GS/Zip GS"):
Quote:
- Should I buy the Sanyo chips? Or WDC ones?
Sanyo re-engineered the 816, but WDC sells them.
- Where can I purchase the high-speed 65816 from?
The Western Design Center, Inc.
...
Each hi-speed 816 is individually tested. All hi-speed 816 are designed to do 12mhz @ stock 5v.
...
- do I really need to increase the voltage?
You can learn to read your shmoo plot by reading the article
sent by WDC. In my case, I was suppose to supply 4.75v - 5.25v
to run at 12.82mhz, 5.5v - 5.75v for 13.51mhz, and 6v for
14.71mhz.
But I'm suppling 5v @ 13.75mhz, and about 5.2v @ 15mhz. Your
requirement might be different.
An update posted in September notes "I'm told they don't require you to get a copy of the article anymore"
And from a September 1996 FAQ (
Frequently Asked Questions (FAQ) for upgrading GS accelerators):
Quote:
Does it really run at 14 MHz?
WDC now has true 14 MHz parts, they will run 14 MHz at the stock 5 V.
It is possible because of the 0.8 micron chip fabrication process.
(formerly 1.0 micron I believe)
If you run it with 5+ volts, higher speeds should be possible.
Note: Apparently, WDC does not warrent these new 14 MHz chips even
though they are production parts. This sucks because the chip I have
does not work correctly even at 12.5 MHz.
But we can get closer -
this Feb 1995 update ("Final (?) update to TWGS/Zip GS Mini-FAQ") contains the above snippets and more:
Quote:
08-22-94 - Major update, availability of true 14 MHz parts!!
...
Price: $19.80 each, minimum order is $100
Availability: shipping now!
Note: All of the chips have been tested to run 14 MHz at 5 volts. Thus the schmoo plot sheet isn't included any more.
...
** ~~9. Do I really need to increase the voltage?
With the new 14 MHz parts, you should not need to mess with the
voltage at all. Unless you want to try 15 MHz, 16 Mhz, or
even 20 MHz.
So, by August 1994 WDC have started selling 14 MHz parts to hobbyists without need for overvoltage but also without warranty.