Path: utzoo!attcan!uunet!husc6!cca!dee
From: dee@cca.CCA.COM (Donald Eastlake)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Knowing Machine Code
Keywords: 68881 emulator.
Message-ID: <29735@cca.CCA.COM>
Date: 20 Jun 88 16:30:49 GMT
References: <13735@comp.vuw.ac.nz> <104700032@uiucdcsp> <4760@husc6.harvard.edu> <13542@shemp.CS.UCLA.EDU> <12217@apple.Apple.COM> <8915@dartvax.Dartmouth.EDU> <12256@apple.Apple.COM> <3514@pdn.UUCP>
Reply-To: dee@CCA.CCA.COM.UUCP (Donald Eastlake)
Organization: Computer Corp. of America, Cambridge, MA
Lines: 20

>In article <12256@apple.Apple.COM> dan@apple.apple.com.UUCP (Dan Allen) writes:
>>One final thought on emulating the 68881: since the 881 uses a lot of
>>the same addressing modes that the rest of the 68xxx family does, an
>>emulator would have to disassemble or correctly emulate ALL of the 68xxx
>>addressing modes, something that takes LOTS of code to do. 

I don't understand why you can't just use the 68xxx hardware to do this.

I.E., couldn't you save a lot under most circumstances by contructing
a 68xxx non-68881 instruction and executing it to fetch/store data rather
than simulating the adressing mode steps?

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-- 
	+1 617-969-9570		Donald E. Eastlake, III
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