Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!prls!mips!earl
From: earl@mips.COM (Earl Killian)
Newsgroups: comp.arch
Subject: Re: RPM-40 microprocessor @ 40 MHz; dat
Message-ID: <1820@gumby.mips.COM>
Date: 9 Mar 88 22:04:31 GMT
References: <9792@steinmetz.steinmetz.UUCP> <9852@steinmetz.steinmetz.UUCP>
Lines: 31
In-reply-to: oconnor@sungoddess.steinmetz's message of 8 Mar 88 20:06:33 GMT


In article <9852@steinmetz.steinmetz.UUCP> oconnor@sungoddess.steinmetz (Dennis M. O'Connor) writes:

   An article by bcase@apple.UUCP (Brian Case) says:
   ] Incidentally, I think MIPS would rather have the R2000 known as a 10 MIPS
   ] machine at 16 MHz (not the 8 MIPS you quoted).

   Actually, I think MIPS Inc. actually claims a 10 Vax-MIPS rating for
   their 16-native-peak-MIPS processor, that uses a 32MHz clock. Which
   places addresses on the address bus once every 30ns. THAT's why
   "MHz" is TOTALLY inappropriate, WORSE than native-peak MIPS, even.
   An RPM40 at 32MHz would also place addresses on the address bus once
   every 30ns, but would execute 32-native-peak-MIPS.

Actually MIPS claims that the M/1000 system product, which uses the
R2000 chip at 15.0MHz with an 8-cycle cache refill penalty, is 10 VUPS
(aka mips).  The R2000 cpu and R2010 fpu chips are 16.7MHz chips.  At
16.7MHz with a faster cache refill, the they make a system with 12
VUPS of performance.  Just wanted to get the record straight.

The MHz figures are for cycle times, not the clock input.  We call the
R2000 16.7MHz because its cycle time is 60.0ns.  The 2x frequency of
the clock input is simply a convenience for generating two phase CMOS
clocking.  Call it a 33.3MHz machine if you want, but that seems
rather silly given that the phase clocks could theoretically be
generated internally from a 1x clock input.

As for judging machines by the rate they put addresses on an address
bus: that's a new one to me.  I think we'll be better off sticking to
how fast machines execute programs.  By that metric, and from what
descriptions of the architecture (which is all there is to go on given
the lack of any hard data), the 2yr old, 2 micron R2000 may well today
outperform the new 1.2 micron RPM40.