Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!bloom-beacon!apple!well!dsmall
From: dsmall@well.UUCP (David Small)
Newsgroups: comp.sys.atari.st
Subject: Re: More on Spectre 128 Problems
Message-ID: <10475@well.UUCP>
Date: 25 Jan 89 08:00:33 GMT
References: <8812300458.AA25156@ucbvax.Berkeley.EDU> <13234@cup.portal.com> <24467@sgi.SGI.COM> <13524@cup.portal.com>
Reply-To: dsmall@well.UUCP (David Small)
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 35


(The base note, which I'll save space by not echoing, concerns
Multifinder on the Spectre 128).
  
  Richard, the reason I don't recommend Multifinder on the Spectre is
that when Multifinder is started up, Multifinder steals away the "bus error"
vector, at location 8, and points it to itself. Many Mac "day to day"
operations generate bus errors on the Atari, from storing into 0 accidentally
because of a pointer gone awry, or a NIL return from an OS trap; to testing
for if the host machine is a Lisa or Mac; to turning sound off and on.
I have a lot of code that the bus error vector points to which examines the
bus error and, if possible, recovers from it; the Magic Sac started getting
really compatible when this code went in, as a surprising amount of Mac
software was generating ST bus errors.
   Thus, when you go into Multifinder, you've disabled all the bus error
trapping that is holding things together. You'll notice that whenever
you exit an application, for instance, you get an "unexpectedly quit ID=1"
message; that's multifinder's bus error handler.

As soon as I jiggle in some code that tests for location 8 being altered,
and fixes it up if so to my code (and then have my code jump to their code
if I can't handle it -- standard vector stuff), Multifinder will probably
stabilize considerably. As is, I'vehad 8 well behaved applications up t
once on my 4-meg ST, and 1.5 of free RAM to go..

Hence, please don't say (as the base note does) that Multifinder won't
ever be supported on Spectre. The product has only been out since
September, and I've had a few things to do..

 -- Many thanks,
Dave Small, Bottlewasher
Gadgets by Small, Inc.

p.s. The hplabs!boulder!tcr!gadgets!dsmall is temporarily down; I'm
trying to fix that... the 7300 is acting up.