Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!edcastle!hwcs!neil
From: neil@cs.hw.ac.uk (Neil Forsyth)
Newsgroups: comp.sys.atari.st
Subject: Re: Fine scrollin'
Keywords: graphics atari helpx2
Message-ID: <4474@brahma.cs.hw.ac.uk>
Date: 21 Feb 90 09:40:22 GMT
References: <1199@elmgate.UUCP> <590@spcc386.UUCP>
Reply-To: neil@cs.hw.ac.uk (Neil Forsyth)
Organization: Computer Science, Heriot-Watt U., Scotland
Lines: 21

In article <590@spcc386.UUCP> stefan@spcc386.UUCP (Stefan Posthuma) writes:
>One last alternative is 'Sync scrolling'. This is a incredibly difficult
>trick that uses a glitch in the Shifter/MMU to open screen borders. Mess
>around properly with them and screen borders will be opened ('Overscan'),
>mess around even more and the physbase will start moving around, scrolling
>the screen, but this is only for the superfreaks amongst us.

I ran a DEMO that does this on an STE and the video hardware really chucked
up on it. The custom chips on the STE no longer have the same quirks as the
old ones so if you don't want to lose compatibilty don't do it. Also the
sync scrolling technique uses frequency toggling and I believe loses on
a native 60Hz display.

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! Neil Forsyth                       JANET:  neil@uk.ac.hw.cs                 !
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