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From: terryl@tekcrl.UUCP ()
Newsgroups: net.micro.68k
Subject: Re: bus error, but why?
Message-ID: <38@tekcrl.UUCP>
Date: Mon, 28-Jan-85 16:01:28 EST
Article-I.D.: tekcrl.38
Posted: Mon Jan 28 16:01:28 1985
Date-Received: Wed, 30-Jan-85 05:32:04 EST
References: <363@nbs-amrf.UUCP>, <3500006@iuvax.UUCP>
Lines: 18

>The problem probably is that you are using an assembler for the 68000
>and not the 68010.  Long words need to be long word aligned when using
>the 68010 whereas they need only be word aligned on the 68000.


     Wrong, assembler-breath. Long words need only be WORD-ALIGNED on the
68010, not long-word aligned. It's still a 16-bit external data bus, not a
32-bit bus. The 68000 is upwards compatible with the 68010, but not the other
way around, software-wise, except for one instruction: the move from status
register, which is now a priviledged instruction under the 68010. It wasn't
under the 68000. Of course this assumes the code is at the user level;
interrupts and exceptions push things on/pop things off the system stack in
slightly different ways between the two processors.


				Terry Laskodi
				     of
				Tektronix