Re: More ZipGS Upgrade Woes!!

[Rubywand <rubywand@swbell.net>]

Marvin Miller writes ...
> 
> Hi Friends;
> 
> I got a new WDC processor for my ZipGS and am having problems with it. I
> suspect it's DOA but could use some more opinions...
> 
> Card works well with the old -7 proc but as soon as I install the new
> W65C816S8PL-14 proc the computer dies.
> When I re-boot with the new chip the screen appears garbled etc. Sometimes
> you can get to see the ROM 3 screen but than nothing. Other times I get an
> error code;
> 
> Fatal System Error 0682
> 
> I mean it's pretty simple - pull one chip & install the new one. I've tried
> several times and the net result is that the old -7 works fine, the new -14
> does not. The pins all look good.
> 
> Just wanted to check to see if there might be something simple I'm missing -
> this happens all the time!!
> 
 ....

     A bad chip is a possibility. It does not seem likely, though.

     One thing to check is the contacts (pins) on the new '816. Look at them under
a magnifier with good lighting and see if you detect any pins that look dull. If
you do find one, try (carefully) scraping the lead with a needle or small jewler's
screwdriver to get shiny metal.

     The new '816 may use different kinds of inputs (requiring different "1" and
"0" voltage levels) in at least a few places. A fairly easy try at fixing things
is to pull the 74F00 and plug in a 74HC00. This is a standard part of speed
upgrades which should probably be done whenever a new '816 is swapped in.

     Something else to check is that your IIgs is not running with low voltages:
especially, low voltage on the +5V line. If you have any power-sucker Slot cards
plugged in and have not done any of the usual power supply and motherboard mods,
you may be getting just enough voltage to run the old '816 but not enough for the
newer version. (A test would be to see if-- with power OFF-- pulling some Slot
cards fixes things.)  For more effects of heavy loading and fixes, see
http://home.swbell.net/rubywand/Csa2POWER.html .



Rubywand