Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!mcgill-vision!bloom-beacon!eru!luth!sunic!mcsun!ukc!edcastle!hwcs!neil
From: neil@cs.hw.ac.uk (Neil Forsyth)
Newsgroups: comp.sys.atari.st
Subject: Res Changing
Keywords: After A Crash?
Message-ID: <3995@brahma.cs.hw.ac.uk>
Date: 21 Dec 89 01:19:32 GMT
Organization: Computer Science, Heriot-Watt U., Scotland
Lines: 31


The other day Dave Baggett asked about legal resolution changes without the
use of system calls like XBIOS #5. Derek Mui (Atari) said basically
'Naw can't be done'. I know GEM can't cope with rez changes.

Let us say that I write an application that if run in medium rez changes to
low and set's the negative Line-A variables appropriatly (as does Neochrome).
Just before exiting I restore things the way they were.
(Note: I don't use GEM while in the new rez)
BUT if my applictaion bombs out before normal termination we get dumped
back to the desktop in low rez. Real bummer!
So we put in a terminate handler at vector 0x102 that restores the original
resolution and Line-A variables. The question is: Can we call the XBIOS
safely from here? If not then we will have to access the hardware ourselves
and set all the variables normally affected by Setscreen. So where are these
variables? Are they, as I suspect, more negative Line-A variables documented
in S.A.L.A.D (Still Another Line A Document)?

Would someone at Atari like to let the cat out of the bag about negative
Line-A variables? Please. It is Christmas.

BTW: Atari UK have yet to send me S.A.L.A.D (Bash, bash, bash ...:-)

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! Neil Forsyth                       JANET:  neil@uk.ac.hw.cs                 !
! Dept. of Computer Science          ARPA:   neil@cs.hw.ac.uk                 !
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