Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!cbnewsm!cbnewsk!ech
From: ech@cbnewsk.att.com (ned.horvath)
Newsgroups: comp.sys.mac.programmer
Subject: Re: System 7.0/Supervisor Mode ?
Message-ID: <1991May15.155912.23810@cbnewsk.att.com>
Date: 15 May 91 15:59:12 GMT
References: <1991May15.024320.9727@world.std.com>
Organization: AT&T Bell Laboratories
Lines: 24

Brian Kendig writes in a message to All

BK> How difficult a modification would it be to have my SE use user 
BK> mode, too?...

From article <1991May15.024320.9727@world.std.com>, by siegel@world.std.com (Rich Siegel):
> 	It's trivial to do, since it only involves changin a single bit
> in the status register, and it'll only break software that depends on
> exception stack frames, but it's a completely useless thing to do on
> a Mac SE, which is neither pre-emptive nor is it capable of supporting
> an MMU directly.

It's useless, unless you're testing your program to see if it MIGHT RUN on
one of those high-end machines you can't afford.  Now, I'm sure Rich&co.
have made sure ThC and ThP won't generate privileged instructions, and that
all that hand-coded library asm code is clean (right, Rich?), but not all
of us know for sure...!

It's also not obvious to me that "just set the bit" is valid (I haven't
tried it) since the ROM on his SE may just have other ideas...
-- 

=Ned Horvath=
ehorvath@attmail.com