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From: gwes@inmet.UUCP
Newsgroups: net.micro
Subject: Re: Intel's Dubious Timings - (nf)
Message-ID: <1359@inmet.UUCP>
Date: Tue, 1-May-84 06:08:23 EDT
Article-I.D.: inmet.1359
Posted: Tue May  1 06:08:23 1984
Date-Received: Thu, 3-May-84 08:19:16 EDT
Lines: 41

#R:intelca:-25300:inmet:5800050:000:1808
inmet!gwes    Apr 30 16:15:00 1984

-Null cosmos est-
Re "typical" speeds & instruction mixes:

Mr. Elliott has a point:  Chip manufacturers have habitually exaggerated
the real usefulness of their products by publishing "typical" timings
in BIG print, and the minimum/maximum (as appropriate) in small print in
the back of the spec sheet.  Anyone who reads such a spec sheet should
look VERY carefully for the words "minimum", "maximum", and especially
"guaranteed".

I have tested four computer models for real execution speed, both in
standalone tests and "typical mixes".  Of course, my typical mix is not
the manufacturers' - I just took the three or four programs which showed
up on accounting runs as taking the major (.gt. 50%) of system time.
In all cases the manufacturers' timings were optimistic, usually by
30% or more.

The reaction of the Intel person (sorry, name rolled off screen) is
unfortunate at best.  Data sheets should CLEARLY represent the real
extremes of performance.  Recently Fairchild and Texas Instruments have
begun documenting their AS, FAST, and ALS TTL lines with MIN and MAX
times only - no "typical".  This is a great service to the engineering
community and should be taken up by all manufacturers.  Too often
I have had to "fix" a design in which the engineer believed the
"typical" timings.

One reason to use a machine like the 286 would be for very high speed
manipulations - perhaps as a coprocessor to a 68K or other useful machine.
(Prejudice shows here...)  The fact that hand-coding a high speed loop
might have no effect because the prefetch was defeated would be an
expensive lesson to learn.

In short - marketing "hype" has no place on data sheets - guaranteed
performance should be the data in big print.  The "typical mix"
is mostly mythical.

	Geoff Steckel
	(inmet!gwes or ima!inmet!gwes)