Article View: comp.arch
Article #10726Re: RISC vs. CISC -- SPECmarks
From: Adam Krolnik
Date: Wed, 08 May 1991 23:06
Date: Wed, 08 May 1991 23:06
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There are problems that no-one seems to be discussing about implementing
super-scalar techniques. They all cost a lot of hardware. Unless you intend
from the beginning for the architecture have a vliw view, the processor has
to perform dynamic instruction selection, and issue. This initial part of
a superscalar processor is very costly in gates and time. True there are
superscalar boxes out there (HP-PA and RS6000) that are fast. But the
superscalar techniques made them large. They are not single chip implementations.
And if they were, the gates they consume could be used to increase performance
by allocating them to other functions. Superscalar gains are a factor of 2-3,
maybe a little larger, but not close to a magnitude. Magnitude gains are achieved by
circuit technology (time) and memory bandwidth.
Adam Krolnik
Design Verification (214)-497-4578
Convex Computer Corp. Richardson Tx, 75080
Disclaimer: What?! Lawyers don't read this stuff do they?
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!convex!krolnik From: krolnik@convex.com (Adam Krolnik) Newsgroups: comp.arch Subject: Re: RISC vs. CISC -- SPECmarks Summary: Superscalar is expensive in silicon and time. Message-ID: <1991May08.230603.20728@convex.com> Date: 8 May 91 23:06:03 GMT References: <819@cadlab.sublink.ORG> <1991May7.061500.7485@marlin.jcu.edu.au> <1991May7.152921.3307@rice.edu> Sender: usenet@convex.com (news access account) Organization: CONVEX Computer Corporation, Richardson, Tx., USA Lines: 18 Nntp-Posting-Host: magnum.convex.com