Re: Apple IIGS monitor replacement

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/

"The wastebasket is our most important design
tool--and it's seriously underused."
.

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