Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!pyramid!voder!apple!landon
From: landon@Apple.COM (Landon Dyer)
Newsgroups: comp.sys.atari.st
Subject: Re: Changes/fixes to OS
Message-ID: <7499@apple.Apple.Com>
Date: 29 Feb 88 16:06:59 GMT
References: <2597@crash.cts.com>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 26

In article <2597@crash.cts.com>, sreeb@pnet01.cts.com (Ed Beers) writes:
> Speaking of following the standards to insure future compatibility, why did
> Atari use the $axxx and $fxxx instruction traps.  These are reserved in the
> mc68000 and the $fxxx instruction opcodes are used by the mc68020 and mc68030.

Line-A was used because, well, Apple used it, and it was there.  Line-F was
used as an optimization (two-byte JSRs so the AES would fit into ROM), and
is in no way related to the way the ST is "defined" to the outside world.

Questions about what IS defined on the ST should probably be directed to
the guy in the hotseat, Mr. Good.  Since the final technical documentation
is over TWO YEARS LATE (!) I'd expect it to be a priority item now.  There
is no substitute for good documentation -- and the ST just doesn't have any
yet.


> This probably explains why the megas come with a 68000 rather than a 68020.

Nope.  The ST is pretty stuck in the mud with respect to the 68000, but for
different reasons.  Moving to a 68020 will be painful for EVERYONE.


-Landon
-- 

I speak for me.