Re: Apple IIGS monitor replacement

["Michael J. Mahon" <mjmahon@aol.com>]

Mitchell Spector wrote:
>     I believe it's a flaw in the video design of the IIgs. RGB video is fine,
> but composite is a mess (excluding emulated 8-bit Apple IIe video). 
> Apple did quietly offer a solution/fix, that was to purchase and install 
> their Video Overlay Card. You get respectable composite video with
> that, without any of the massive color shifting and color inaccuracies.
>
> I took some quick snapshots to (roughly) show the difference:
>
> Apple IIgs composite-out (built-in port):
> http://raptor.golden.net/~mspector/IIgs-composite.jpg
>
> Apple IIgs composite-out (Video Overlay Card):
> http://raptor.golden.net/~mspector/IIgs-VOC.jpg
>
> Apple IIgs RGB-out (AppleColor RGB):
> http://raptor.golden.net/~mspector/IIgs-RGB.jpg

These are very interesting.  I've never seen a IIgs hooked up to
a composite monitor, so it's interesting to see how the 8MHz and
16MHz dot clock affect it.

>     Sorry about the poor quality, this is my Sony 27" TV set from 1989
> snapped with a cheap digital camera. Notice how the Video Overlay
> card output gives you readable text in the Finder desktop. And 
> although you can't see it here, it's also more accurate for color.
> Obviously the RGB monitor is the nicest output of all.

Taking photos of CRT monitors is always problematic, because for
common shutter speeds, the screen is refreshed about once and a
fraction times, causing big differences in exposure on one side
of the fractional refresh or the other.

The key to "pretty good" CRT photos is to use a slow shutter speed
(and, of course, close the aperture to maintain correct exposure).
A shutter speed around 1/15 sec will delive about 4 refreshes at 60Hz,
which means that the "edges" of the refresh will only differ in exposure
by 25%--usually tolerable.  1/10 of a second, or even 1/4 second
work even better, but require either a tripod or a stable support
to prevent blurring.

<snip>

> > Or is there a way to force the GS to display 640 mode in monochrome...?
>
>
>     Absolutely. Go into the Control Panel, choose the 'Display' option. 
> Under "Type:" switch it to 'Monochrome'. This *only* has an affect on
> composite output, it does absolutely nothing to an RGB display.

That's good--I wasn't sure that the IIgs could do that.

-michael

NadaPong: Network game demo for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

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