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From: keen@ee.ualberta.ca (Jeff '876393' Keen)
Newsgroups: comp.sys.apple2
Subject: Re: More extended graphics on the IIgs
Message-ID: <1991Jan23.174647.1393@ee.ualberta.ca>
Date: 23 Jan 91 17:46:47 GMT
References: <1991Jan18.170510.1@gacvx1.gac.edu> <14908@smoke.brl.mil> <1991Jan20.123430.7039@ee.rochester.edu> <14923@smoke.brl.mil> <1991Jan23.172549.1096@ee.ualberta.ca>
Sender: news@ee.ualberta.ca
Organization: University of Alberta Electrical Engineering
Lines: 28

In article <14923@smoke.brl.mil> gwyn@smoke.brl.mil (Doug Gwyn) writes:
>In article <1991Jan20.123430.7039@ee.rochester.edu> seah@ee.rochester.edu (David Seah) writes:
>>Not having a VOC myself, what is it about this board that messes up
>>3200 color demos?
>
>Basically, in order to synchronize with an external video source, it
>provides a duplicate IIGS video subsystem that is not synchronized to
>the one on the motherboard.  Unfortunately the existing 3200-color
>demos use the motherboard clock-based signals to coordinate their
>updates of scan-line control bytes during the painting of the image.
>The effect is that the VOC is using the wrong SCB information since
>it is updated out of sync with the VOC scanning.

One thing you may want to try is to plug the composite video output into
the VOC so it is synched with the computer.  This may correct the problem
but I don't have a VOC so I can't tell.  If reconectting cables isn't
what you desire add a video switching unit so you can switch between
video to be overlayed and the computers composite output.  This is 
assuming the VOC synchs to composite video not a single wire synch
signal used in production houses.



-- 
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Jeff Keen    University of Alberta
keen@bode@alberta                  
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