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From: finkel@TAURUS.BITNET
Newsgroups: comp.sys.amiga.emulations
Subject: Re: Emulator Mechanics (sorry long post)
Message-ID: <2407@taurus.BITNET>
Date: 9 Mar 91 21:55:47 GMT
References: <4992@mindlink.UUCP> <1991Mar6.004247.8964@cpsc.ucalgary.ca>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: finkel%math.tau.ac.il@CUNYVM.CUNY.EDU (Udi Finkelstein)
Organization: Tel-Aviv Univesity Math and CS school, Israel
Lines: 10

One important fact I forgot to mention is that an IBM emulator running
on a 68020 or a 68030 based machines can safely use 16 bit arithmetic
operation on memory operands on located on byte boundary addresses, unlike
the 68000 which requires word and longword operands to be word aligned.
since the 8088 instruction set allows word operands to be stored on byte
alignment, emulating these instructions on a 68000 requires splitting
the memory access to two seperate byte memory accesses or one longword
memory access followed by a shift operand.

Udi