Re: IIgs ROMs revisited from a Collector's Perspective

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

Justin Scott <djnospam@impakt.net> wrote:

> Wayne Stewart <waynes@intergate.bc.ca> wrote:
> > You don't need a VGC. The only reason they included a VGC in the upgrade is
> > that quite a few of the early ones were defective. I've upgraded a few
> > ROM 00s but have yet to run into a VGC that was actually defective.  I
> > likely have some eary issue VGCs around but since they aren't defective,
> > the only difference between them and any later ones is the part number
> 
> If I understand you correctly, if someone has the newer VGC, and swaps the
> ROM 01 with the ROM 00, bad things will not happen?

No problem at all.   The only issue with the older vs newer revision of
the VGC is a cosmetic issue with the display.  There are no software
compatibility issues.

The main symptom of the faulty VGC is that the monochrome double hi-res
graphics mode shows pink stripes and/or pink flickering instead of white
for some pixels.  The most obvious example is the MouseDesk (Apple II
Desktop) software, which shows a pink background instead of grey.

Some VGCs (including the one from my "Woz" IIgs) produced the same
symptoms in 80-column text mode, with the effect varying depending on
the foreground and background colours set in the control panel.  (Mine
was OK with white text on a blue background, but I got pink flickering
if I tried to use a black background.)

My VGC was upgraded along with my ROM in 1988.  I managed to keep the
ROM 00 chip, but not the VGC.  I've put the ROM 00 chip back in the
machine on at least one occasion since then, and it works fine with the
fixed VGC.

> I have no shortage of ROM 01 boards available to me.  Question now is...
> Where can I obtain a known working ROM 00 chip, and how much would the owner
> charge for it? :)

Sorry, mine is not for sale.