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From: vsnyder@jato.jpl.nasa.gov (Van Snyder)
Newsgroups: comp.sys.atari.st
Subject: Re: TT upgrades
Summary: Clarify earlier remarks re 680x0 / 88000
Keywords: 88000
Message-ID: <1991Feb8.204957.10770@jato.jpl.nasa.gov>
Date: 8 Feb 91 20:49:57 GMT
References: <1991Feb7.213305.26568@jato.jpl.nasa.gov> <16037@milton.u.washington.edu> <1991Feb8.010109.396@jato.jpl.nasa.gov> <1991Feb8.064335.26267@cs.ucla.edu>
Reply-To: vsnyder@jato.Jpl.Nasa.Gov (Van Snyder)
Distribution: na
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 34

1.  Speed.  I don't count how many instructions are executed per second.  I
    haven't looked at the output of a compiler more often than twice per year
    since about 1970.  I look at how fast a given program gets executed.  At
    the same clock rate, the 88000 gets done twice as fast as the 68040.
2.  REAL customer:  A stable company with a good reputation that buys several
    hundred thousand or more of some particular part, e.g. 68030 or 88100, per 
    year, year after year.  By this measure, Atari is not a REAL Motorola 
    680x0 customer -- too small a player (several tens of thousands at most).
3.  CAMMU means "Cache And Memory Management Unit", presently a separate chip.
4.  I know that 200 Mhz means 5 ns clock, and that a Y-MP has a 6+ ns clock.
    But it also has MILES of wires.  The Fujitsu VP-200 has a 2+ ns clock.
    The 88xxx is built on a 1+ cm die, so no wire is longer than about 2cm,
    about .17 ns.  The Y-MP has 64 bit paths, and TERRIBLE arithmetic.  The
    88110 has 80 bit data paths, and IEEE arithmetic (much better than the
    junk Cray calls arithmetic).  With SuperScalar and Multi-Pipelining,
    the 200 Mhz 88110 will be faster than a Cray 1-s, and at $1000 (initially)
    will cost al LOT less.  When the price inevitably comes down to $50,
    who would prefer a 68090 that costs the same (give or take $5), but runs
    half as fast at the same clock rate?  (The "half as fast at the same clock
    rate" part is inevitable:  The 680x0 instruction set REQUIRES hazards in
    the pipeline that INEVITABLY slow it down, except at the expense of
    ENORMOUS numbers of transistors.  To achieve the same speed as an 88xxx,
    a 68xxx will need 2-4 times as many transistors, and therefore ultimately
    COST A LOT MORE.)
5.  My first hand calculator was an HP "Digital Slide Rule", 6 digits, add,
    subtract, multiply, divide.  No square root.  $600+.  They GIVE you a
    better calculator now if you buy a toaster at K-mart.  I don't think the
    price of 88xxx chips will be FOREVER greater than the price of 68xxx
    chips, if for no other reason than the 88xxx has fewer transistors!

-- 
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