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From: baum@Apple.COM (Allen J. Baum)
Newsgroups: comp.arch
Subject: Re: RISC definition
Message-ID: <40706@apple.Apple.COM>
Date: 3 May 90 16:40:19 GMT
References: <2756@sunquest.UUCP> <151@exodus.Eng.Sun.COM> <1192@m1.cs.man.ac.uk> <1990Apr27.161912.15649@robohack.UUCP> <1252@m1.cs.man.ac.uk>
Reply-To: baum@apple.UUCP (Allen Baum)
Organization: Apple Computer, Inc.
Lines: 40

[]
>In article <1252@m1.cs.man.ac.uk> mshute@cs.man.ac.uk (Malcolm Shute) writes:
>>In article <1192@m1.cs.man.ac.uk> I wrote:
>>>[A suggestion that we should define a metric so that RISC vs CISC was
>>>no longer a black/white issue, but a sliding scale, say from 0.0 to 1.0]
>
>Since measuring the instruction set complexity directly has been shown
>to be unworkable (the reductio ad absurdum above), suppose we were to
>adopt an indirect method.  Suppose we were to define a metric which is
>the quotient of:

As the guy said in the movie "Big": I don't get it.
Why do you need this metric? Will you use it to decide which processor to buy?
This is a bad idea. You should pick a processor on the basis of things like:
  cost
  performance (for YOUR application mix!!!!!)
  ease of integrating into a system
  software base
  support chips
  second sources
  whether you think the supplier will be around in a few years
  ease of working with the supplier
  architectural upgrade paths
  how easy/hard performance upgrades will be
  how easy/hard next-generation will be to design
  (add your own-- I'm curious what other people think are important)

These are not in priority order. The order depends on what is important to YOU,
like the application mix, which is specific to YOU.

If a CISC were to come out ahead by the above metrics (which don't even care
about what the instruction set looks like, you'll notice), which should the
RISC/CISC label make a difference? Like, who cares?

Again, my point is that RISC is a design philosophy that, if used, will allow
a processor design to look its best, using the above metrics.

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