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Path: utzoo!linus!decvax!ittvax!bunker!chuck
From: chuck@bunker.UUCP (Chuck Heaton)
Newsgroups: net.micro.apple
Subject: hires_question
Message-ID: <494@bunker.UUCP>
Date: Thu, 9-Aug-84 10:31:29 EDT
Article-I.D.: bunker.494
Posted: Thu Aug  9 10:31:29 1984
Date-Received: Fri, 10-Aug-84 08:18:34 EDT
Lines: 24

	Hi.

	Somewhere, I read about a simple modification to the
Apple II (maybe also II+, IIe, or IIc) that effectively doubled 
the horizontal screen resolution for Hi-res graphics. The general
idea was somehow tying the vertical (or horizontal ???) retrace
signal to the 'bit' that selects page 1 / page 2. After making
this modification, which I vaguely recall involved a single
jumper and perhaps a single trace cut, the two 'pages' would
automatically flip upon each vertical (I think) retrace. Although
other effects are also possible, the particular effect that I
was interested in was the above-mentioned doubling of the
horizontal resolution for graphics. All pixels on one page are
done with bit 7 low, and on the other page with bit 7 high (thus
causing the half/pixel horizontal shift. I am not particularly
hardware oriented, although I'm not a complete idiot either. If
anyone knows how or can figure out how to perform this (possibly
warrenty voiding - horrors) modification, could you please post
it to the net or mail it to me directly. In return, I would be
glad to submit (once working) source to replacement 6502 routines
to allow Applesoft (or whatever) to take advantage or this
capability (these routines are fairly easy to write). Thanks.

					Chuck Heaton