Re: Limited Edition GS's (Was: Re: Old v. late IIc)

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

In article <C071096132053.89@cottage.ecore.fnet.org>,
Tinman@cottage.ecore.fnet.org (Tinman) wrote:
>In Article <4rt1je$6ar@atlantis.atlantis.actrix.gen.nz>,
><dempson@atlantis.actrix.gen.nz> wrote:
>
>My "Woz" GS does have ROM 01. However, I don't know about the faulty
>VGC. How would I know if I had it?

The easiest way to tell is to run "MouseDesk" or "Apple II Desktop" (IIgs
System 1.0, 1.1 or 2.0).  With a faulty VGC, the desktop area has pink
areas (possibly in stripes, possibly flickering) instead of being
reasonably clean grey.

Other programs that use monochromes double hi-res graphics (560x192
black/white) will exhibit similar problems: flickering pixels, or pink
appearing in place of grey.  There is no problem that I am aware of with
colour double hi-res graphics (140x192 in 16 colours).

On my machine, I had similar problems in 80-column text mode, but it was
less obvious.


You can also look at the part number on the VGC (it is the socketed PLCC
chip under the power supply).  I don't have the original chip any more, so
I'm not sure exactly how it was labelled.  The replacement chip I got is
"344S0046-C".  I think the original was "344S0046-0" or "344S0046-A".  I
have heard of other versions as well, but I don't know what differences
there are.  It is only the original version which has the display problem
in double hi-res and/or text mode.

The ROM 3's VGC has a different part number, isn't socketed, and doesn't
have this problem.

>I don't think I've ever used double hi-res mode, but should the need
>somehow arise, I would like to know how to fix the problem.

The only way to fix the problem is to replace the VGC with a newer one.

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, NEW ZEALAND