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From: johnv@sequent.com
Newsgroups: comp.arch
Subject: Re: 2.5 Addr Archs
Message-ID: <1991May9.151545.8918@sequent.com>
Date: 9 May 91 15:15:45 GMT
References: <673707950@romeo.cs.duke.edu> <165@armltd.uucp>
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>>From: firth@sei.cmu.edu (Robert Firth)
>>Subject: Re: Clarification on 3 Addr vs 2 Addr Archs
>>Date: 8 May 91 13:08:16 GMT
>>
>>Sigh.  Let me point out first that one cannot decide which
>>architecture is "best" in isolation.  It is necessary to
>>consider application domain, programming language, language
>>use styles, compiler effectiveness, and a host of hardware
>>issues.

I agree with all of this but the last ... that hardware issues must be
considered.  The idea of an instruction set is that it must be capable of
being implemented and realized (using the Blaauw nomenclature) with many
different ways.  Take for example the VAX and the IBM 360 instruction sets.
Or even the MIPS instruction sets which have now had at least 4 different
implementations in several different technologies.

An instruction set is just a language for describing the 'meaning' of a 
program, which in turn is a language for describing a solution to a problem.
The effectiveness of the languages for being mapped to from the next higher
up languaage is what should be considered.

-- 
John Van Zandt
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