Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!udel!princeton!phoenix!pupthy2!lgy
From: lgy@pupthy2.PRINCETON.EDU (Larry Yaffe)
Newsgroups: comp.arch
Subject: Re: RISC  a short answer??
Message-ID: <2810@phoenix.Princeton.EDU>
Date: 7 May 88 18:38:00 GMT
References: <1036@nusdhub.UUCP> <1988May3.224604.2252@utzoo.uucp> <383@m3.mfci.UUCP> <1988May5.171444.849@utzoo.uucp> <9341@apple.Apple.Com>
Sender: news@phoenix.Princeton.EDU
Reply-To: lgy@pupthy2.PRINCETON.EDU (Larry Yaffe)
Organization: Physics Dept, Princeton Univ
Lines: 43

In article <9341@apple.Apple.Com> bcase@apple.UUCP (Brian Case) writes:
>In article <1988May5.171444.849@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
>>Reduced Instruction Set means fewer and less complex instructions.  That
>>is all it means.
>
>Wow, I didn't think I'd ever see this comment.  [...]
>let me now give my personal, back-of- the-business-card summary of RISC:
>1)  Uniform Pipeline (all, or nearly all, instructions flow through the
>pipeline in the same way)
>2)  Good match to optimizing compiler technology (the architecture makes it
>easy for the compiler in several ways:  code generation, code motion,
>register allocation, etc., and *calculating the cost of code sequences* in
>both time and space)
>3)  Allows technology to be exploited (cycle time dominated by some
>"irreducible" component of computation like an ALU or Cache lookup; yes, I
>know you can pipeline ALUs and cache lookups, but do you really want to?)

    These all seem like reasons for "Why RISC is a good thing",
not at all part of the basic definition of what RISC stands for.
Seems to me that Henry summed up what RISC
means pretty well - fewer instructions.

>RISC is a way of doing things, not a thing.

    This sounds like usurping the name of something specific
(Reduced Instruction Set) for a much more general
philosophy (into which it naturally fits).
I'd call that a misleading choice of terminology.
But then I don't have any simple acronym which
sums up a philosophy of "keep things simple,
devote resources & effort where they produce the
most benefit".  (Except for "common sense" :-))

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------------------------------------------------------------------------
Laurence G. Yaffe			lgy@pupthy.princeton.edu
Department of Physics			lgy@pucc.bitnet
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