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From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.atari.st,comp.sys.misc,comp.sys.amiga
Subject: Re: Atari Transputers ? & A British ST/Amiga Rival ?
Message-ID: <29839@sun.uucp>
Date: Fri, 2-Oct-87 14:19:13 EDT
Article-I.D.: sun.29839
Posted: Fri Oct  2 14:19:13 1987
Date-Received: Tue, 6-Oct-87 05:34:24 EDT
References: <8709181728.AA13664@ucbvax.Berkeley.EDU> <1623@gryphon.CTS.COM> <607@sbcs.UUCP> <1138@water.waterloo.edu>
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Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
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In article <1138@water.waterloo.edu> (Lee Dickey) writes:
>You seem to imply that RISC mips are not quite as good as some other kind
>of MIPS.  Are RISC mips slower somehow?  Are more instructions needed to
>produce the same results?   Explain, please.

MIPS is by definition, millions of instructions per second. Unfortunately,
when you compare two different architectures the value of MIPS becomes
meaningless because the instructions may not be equivalent. Typically,
a RISC processor requires more instructions to accomplish a given computation
than a CISC processor, so if both compute the same value in the same amount
of time, say 1 second, it is only natural to want to rate them at the same
'computational power'. However if you compared the number of instructions
that both processors had executed in that instruction you would find that
the RISC processor had executed 10 to 50% more instructions. To get around
this problem many people in the industry have picked the DEC VAX 11/780 as
a 'standard' of 1 MIPS. (Note the added connotations to the MIPS unit of
measurement that are not explicitly stated.) There are several known programs
(both synthetic benchmarks and applications) that have been run on the 
VAX and carefully measured. These same programs can be run on the processor
under test and the results measured and compared to the VAX numbers and then
some estimation of "Vax MIPS" can be deduced. When everyone does this you 
can compare the "MIPS" number of each system and determine relative compute
power. 


--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.