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From: jbickers@templar.actrix.gen.nz (John Bickers)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: 8-bit death
Message-Id: <3691.tnews@templar.actrix.gen.nz>
Date: Tue, 13 May 1991 06:54:42 GMT
References: <3515.tnews@templar.actrix.gen.nz> <1991May10.183627.29486@neon.Stanford.EDU> <3626.tnews@templar.actrix.gen.nz> <1991May12.181436.20304@NCoast.ORG>
Organization: TAP, NZAmigaUG.

Quoted from <1991May12.181436.20304@NCoast.ORG> by allbery@NCoast.ORG (Brandon S. Allbery KF8NH):

> TRAP is slower, but JSR doesn't switch the processor to supervisor state.
> Yes, Unix runs the kernel in supervisor and user programs in user mode.  Why
> do you think Unix programs core dump instead of guru-ing?

    I thought part of that had to do with using MMUs. Except for the fact
    that Amiga programs can blat into sensitive places (the Blitter,
    etc), why not control reads/writes with the MMU, and use the TRAPs
    for trapping what they're supposed to trap like GOMF does already?

> |     If it is, it is also well hidden by the system (as it should be)
> |     compilers. MS-DOS's aren't.
> +---------------
> 
> Actually, 680x0 Unix usually puts the system call in d0.

    Nevertheless, hidden. I haven't noticed an intfoo() function in
    a Unix compiler yet.

> |     In any case, I'm surprised. Is the Amiga OS the only rational one
> |     in this bunch, eh?

> I don't consider running all programs in supervisor mode "rational".  Does/did
> the Atari ST do this?  The Mac does, and it shows.

    Does the Amiga? I'm as sure as I ever am about anything that it
    doesn't.

> ++Brandon
--
*** John Bickers, TAP, NZAmigaUG.        jbickers@templar.actrix.gen.nz ***
***         "Endless variations, make it all seem new" - Devo.          ***