Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!mcvax!hp4nl!ruuinf!verwer
From: verwer@ruuinf.cs.ruu.nl (Nico Verwer)
Newsgroups: comp.sys.atari.st
Subject: Re: Screen Savers
Summary: monochrome; zeroed memory
Message-ID: <1358@ruuinf.cs.ruu.nl>
Date: 2 Jun 89 08:39:39 GMT
References: <8906011513.AA02186@Fourier.sparta.com>
Organization: Univ of Utrecht, Dept of CS
Lines: 22


If I remember well, the problem with idle1.2 on monochrome systems is
that it sometimes can't find an area in memory filled with zeroes.
In that case idle just reverses black and white instead of turning off
the display. My suggestion is the following: Somewhere high up in
memory there is a region that seems to be filled with FFFF. Actually
these are the cartridge port addresses. Is it possible to write a screen
saver that maps the video ram to this area and changes the palette so that
a 1 is displayed as a black pixel? Of course this cannot work with 
something connected to the cartridge port, but it would do for many
ST-users. A possible problem could be that the pointer in the video-chip
can only be made to point to the first 4 meg. Even on < 4 meg systems 
this is a problem, since this area of memory looks like it is filled
with something like f0BA.
Suggestions, anybody?

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