Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!decwrl!nsc!pyramid!cbmvax!valentin
From: valentin@cbmvax.commodore.com (Valentin Pepelea)
Newsgroups: comp.sys.m68k
Subject: Re: 68040 not object code compatible?
Message-ID: <9816@cbmvax.commodore.com>
Date: 25 Feb 90 04:51:36 GMT
References: <300003@hpclkms.HP.COM>
Reply-To: valentin@cbmvax.cbm.commodore.com (Valentin Pepelea)
Organization: Commodore, West Chester, PA
Lines: 32

In article <300003@hpclkms.HP.COM> ken@hpclkms.HP.COM (Ken Sumrall) writes:
>I just got the 68040 User's Manual, and was perusing the appendix which
>discusses the various features of the different members of the 68000 family.
>In the table on page A-3, the CALLM instruction is shown to be implemented
>only on the 68020.  However, on page 1-1, the 68040 is claimed to be
>user object code compatible with previous members of the 68000 family.

To my understanding, the CALLM and RTM instructions were really meant to be
operating system intructions only. Can you see any uses for these instructions
in an application program? I don't.

>What gives?  Does the phrase "user object code compatible" mean "mostly
>user object code compatible"?

If you want to express dissatisfaction with user object code compatibility,
I suggest you mention the missing floating point instructions in the 68040.
Motorola has the FPSWP (Floating Point Sowftware Package) which is supposed
to terminate the unimplemented floating-point instructions in software. When
I called them to find out what we have to do to get it, I was told $xxxx
please. Not that it's much, it isn't. But since we'd have to provide
something like that in the operating system we release with an 040, it makes
the claim "fully user object code compatible" rather, ahem, incomplete.

I know, I know, the response to that is going to be "we didn't mean to
include the coprocessor". *sigh*

Valentin
-- 
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