Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uwmcsd1!marque!uunet!portal!atari!apratt
From: apratt@atari.UUCP (Allan Pratt)
Newsgroups: comp.sys.atari.st
Subject: Re: A scheme for updating/patching gemdos
Message-ID: <1148@atari.UUCP>
Date: 31 Aug 88 18:52:48 GMT
References: <3377@crash.cts.com>
Reply-To: apratt@atari.UUCP (Allan Pratt)
Organization: Atari (US) Corporation, Sunnyvale, California
Lines: 23

In article <3377@crash.cts.com> sreeb@pnet01.cts.com (Ed Beers) writes:
> After reading lots of messages on the merits of using the 0xAxxx 
> ***RESERVED*** instruction trap, I have to add my 2 cents.  Using the 0xAXXX
> or 0xFXXX traps is bad news.  It limits compatibility with future 68000 family
> products.  Apple atleast avoided using the 0xFXXX trap which is why they have
> had 68881 support for sometime while we still only have somewhat kludged,
> semi-supported floating point support much less a 68020/68030 version of the 
> ST.

Don't be silly.  Using line-F has nothing to do with upward mobility
of the ST to 68020/68030, because such machines will have more ROM space,
so Line-F won't be necessary.  It does make plugging a 68020 into
an ST tough, but that's already tough because of stack frame differences.
Somebody in Germany did it... I don't know how they got rid of Line-F
and still crammed the OS into 192K of ROM, but they did.

Motorola explicitly reserved the $Axxx instructions for machine-specific
use (as opposed to "reserved for Motorola use" like $Fxxx), so Atari
isn't stepping on any toes there.

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt