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From: hyc@math.lsa.umich.edu (Howard Chu)
Newsgroups: comp.sys.atari.st
Subject: Re: Union Demo, Carebears, etc.
Keywords: 50 Hz
Message-ID: <1990Jul13.225929.7675@math.lsa.umich.edu>
Date: 13 Jul 90 22:59:29 GMT
References: <1661@mwca.UUCP> <1990Jul13.222947.10562@wam.umd.edu>
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Organization: University of Michigan Math Dept., Ann Arbor
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In article <1990Jul13.222947.10562@wam.umd.edu> dmb%wam.umd.edu@uunet.uu.net (David M. Baggett) writes:
>On a related note, I've found that a lot of games from acros the pond
>don't work with my Atari monitor (SC1224 or whatever), but DO work on
>other peoples' monitors (also SC1224 or whatevers).  Mine is different
>in that it's vintage 1986; an "old style" monitor.  When running some
>games, the screen rolls horrendously.  (Bill's vertical hold fix works
>on mine too, but you should see the desktop after you diddle with your
>monitor that way!)
>
>Anybody know what it is that these hackers are doing that mucks up
>the screen?  (Examples of programs that do not work: Afterburner, 
>Blood Money)
>
>Dave Baggett
>dmb%wam.umd.edu@uunet.uu.net

I remember this occasionally happening with my SC1224 on the old Rex
demo. I figure they were probably trying to up the vertical resolution
or something. (I'd achieved the same in my 8-bit Atari days by messing
with the display list. Try to draw too many scanlines, instead of leaving
X number black at the top & bottom of the screen, and the picture rolls.)

Rex demo also scrolls colors across the overscan region, so they must
at the very least be messing with the display enable signal. (By toggling
the screen between two scan rates. Probably 50 & 60hz.)

I'm going to have to try Afterburner again, I don't remember it working
on my system either. Oh well.
--
  -- Howard Chu @ University of Michigan
  one million data bits stored on a chip, one million bits per chip
	if one of those data bits happens to flip,
		one million data bits stored on the chip...