Fixing games that reboot

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Article #7574

#7574

From: David Phillip Oster
Date: Fri, 10 Oct 1986 17:27

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Games reboot the machines in one of two ways on the Mac:
either by a Motorola 68000 
	RESET instruction ;the hex for this is 4E70
or via a 
	JMP.L $40000A .;this latter is what apple recommends programs do
Remember that you can jump to 40000A using many addressing modes.
You can fix the rebooting by searching for the offending bytes,
disassembling a little bit around them to make sure your right, and
replacing the RESET or the JMP opcode  by $A9F4, 
(The Mac instruction ExitToShell, the approved program _exit() routine.)
FEDIT is a good tool for finding and fixing the problem.  

	Always work on a copy, don't risk screwing up either your master
disk or your hard disk until you're sure the fix works.

	Note: Many games, among them GridWars, screw up the environment,
so that even if you quit, you can't safely do anything BUT reboot.

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Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!cmcl2!yale!husc6!think!nike!ucbcad!ucbvax!jade!lapis!oster
From: oster@lapis.berkeley.edu (David Phillip Oster)
Newsgroups: net.micro.mac
Subject: Fixing games that reboot
Message-ID: <1430@jade.BERKELEY.EDU>
Date: Fri, 10-Oct-86 13:27:58 EDT
Article-I.D.: jade.1430
Posted: Fri Oct 10 13:27:58 1986
Date-Received: Sat, 11-Oct-86 21:24:37 EDT
References: <7923@sun.uucp> <8012@sun.uucp>
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Reply-To: oster@lapis.berkeley.edu.UUCP (David Phillip Oster)
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