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Path: utzoo!watmath!watnot!watcgl!onfcanim!dave
From: dave@onfcanim.UUCP (Dave Martindale)
Newsgroups: comp.unix.questions
Subject: Re: desktop super computers
Message-ID: <15010@onfcanim.UUCP>
Date: Tue, 11-Nov-86 14:16:56 EST
Article-I.D.: onfcanim.15010
Posted: Tue Nov 11 14:16:56 1986
Date-Received: Wed, 12-Nov-86 01:00:20 EST
References: <4631@brl-smoke.ARPA> <15800022@datacube>
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Organization: National Film Board / Office national du film, Montreal
Lines: 27
Summary: 

>How about a sun 3/260? Its rated at 4 MIPS (68020 running 25 MHz)

4 MIPS running what kind of instructions?

If you take a VAX 11/780 as being a "1 MIPS" machine, I haven't seen
any benchmark that rates anyone's 16MHz 68020 as 2.5 times a VAX 780.
Running the "Dhrystone" non-floating-point benchmark, a Sun 3/160 is
just about 2.2 times an 11/780.  This would indicate that a 25MHz
68020 should be at most 3.3 MIPS doing integer stuff.

My experience with the Weitek 1164/1165 floating point chips, which I
believe is what is used by Sun's fast floating point board, suggest
that they are slightly slower than the 11/780's FPA in both single and
double precision.  And the 780 is less than 1 MIPS when it comes to
floating point.  Also, the Weitek chips force some things to be done
in software that the VAX FPA does in hardware: integer/float conversions,
short/long floating conversions.  The Weitek's greater error (results
are not always exact even when the true result is representable exactly;
e.g. 500.0/10.0 != 5.0) also means extra work for software.  So I'd
be surprised to find any such machine beating a 780 in real applications,
unless it was using single precision on the 68020 and double precision
on the VAX.

Can anyone post *real*, meaningful numbers for the 3/260?

	yours for meaningful MIPS,
	Dave Martindale