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From: dolf@idca.tds.PHILIPS.nl (Dolf Grunbauer)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Assembler Programming - Costs versus Benefits
Message-ID: <536@ssp9.idca.tds.philips.nl>
Date: 30 Nov 90 07:38:19 GMT
References: <1990Nov25.040121.10773@zorch.SF-Bay.ORG> <1990Nov25.233007.19698@cs.umu.se> <7139@sugar.hackercorp.com> <1990Nov27.004859.16630@cs.umu.se> <7150@sugar.hackercorp.com> <CEDMAN.90Nov28142350@lynx.ps.uci.edu> <7160@sugar.hackercorp.com>
Reply-To: dolf@idca.tds.philips.nl (Dolf Grunbauer)
Organization: Philips Information Systems, Apeldoorn, The Netherlands
Lines: 25

In article <7160@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes:
<In article <CEDMAN.90Nov28142350@lynx.ps.uci.edu> cedman@golem.ps.uci.edu (Carl Edman) writes:
<> A correct 68000 program runs unchanged on a 68030.
<
<Ah, then explain why Atari ST programs don't run on a 68020. There are lots of
<instructions that work differently between the 68000 and 68030, and any program
<that uses them will behave differently on different machines.

Could you please give details about the User instructions (i.e. instructions
which can be made when running in User mode, not Supervisory mode) which
behave differently on a 68000 and a 68020 [or 68030] ? I think only
"move from SR" now traps but the OS should take care of this.

<"but those aren't correct 68000 programs", which is all well and good but in
<the real world these instructions exist and are percieved as being useful to
<the sorts of folks who write manic games in assembler.

Aha, one difference might be that these guys are writing self modifying code
which may not work on a 680[234]0 as the changes go into the data cache not the
main memory or instruction cache.
-- 
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