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Path: utzoo!mnetor!seismo!mcvax!botter!ark!Patrick
From: Patrick@ark.cs.vu.nl (Patrick van Kleef)
Newsgroups: comp.sys.atari.st
Subject: Mac Emulator (idea!)
Message-ID: <870@ark.cs.vu.nl>
Date: Tue, 23-Dec-86 21:12:12 EST
Article-I.D.: ark.870
Posted: Tue Dec 23 21:12:12 1986
Date-Received: Wed, 24-Dec-86 21:11:36 EST
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 27
Keywords: Preventing bus errors

*** MUNCH MUNCH MUNCH ***

Just an idea:

The most frequent error that occurs using the Mac Emulator, is a
bus error. This happens when programs start writing at locations they're
not allowed to on the Atari ST. Usually it means the software wasn't
'perfect', not in accordance with the Apple Programming Guidelines.

People tell me there is a way of preventing bus errors on the ST. This
type of error is generated by one line of the Glue chip, the so called
BERR line.

Now what if we disconnected that line? In theory bus errors would be
impossible. Would it affect 'normal programs'? Will more Macintosh programs
run? Is there anyone who can figure this out?

Dave Small writes, the most frequent error is the bus error that occurs when
Mac programs write at location 0, Ram at the Mac, Rom at the ST. This action
has -as far as I know- no effect on the working of a program on the Mac. But
on the ST, a bus error occurs and the program fails to run. Would a switch,
that disconnects the BERR line on the Glue have the same effect as on the
Mac. Namely that programs run without further failure? I think it would
increase the amount of good working Mac software a lot.

As I'm too much of a kludge concerning hardware (and software too, for that
matter), I'd like the opinion of some experts. Moshe, do you have any idea?