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From: braner@batcomputer.UUCP
Newsgroups: comp.sys.atari.st
Subject: Re: Comparison of C Compilers on Different Machines
Message-ID: <1290@batcomputer.tn.cornell.edu>
Date: Sun, 7-Jun-87 10:28:01 EDT
Article-I.D.: batcompu.1290
Posted: Sun Jun  7 10:28:01 1987
Date-Received: Mon, 8-Jun-87 03:52:09 EDT
References: <106@asr2.UUCP>
Reply-To: braner@tcgould.tn.cornell.edu.UUCP (braner)
Distribution: world
Organization: Cornell Theory Center, Cornell University, Ithaca NY
Lines: 23
Keywords: 520ST, ATT 6300+, VAX, Absoft, 68881
Summary: 68020 68881 68020 68881 68020 68881 68020 68881

[]

The only way to get decent number-crunching performance, especially when
transcendental functions are needed, is to use a floating-point chip.
(That AT&T machine must have a '287 chip that the MS compiler uses.)
While the 32081 chip I'm using on the ST yields speeds comparable with the AT
(when used via Absoft FORTRAN), the very best choice is the 68020/68881
combo, the most powerful chip set in existence for personal machines.
(I can see the flames coming from fans of the '386...)  That combo is used
in the Mac II and in "workstations" such as the Sun.  Now if Atari ever dropped
that stupid IBM-PC clone project (which is now 2 or 3 generations behind the
times!) and developed a 68020/68881 box under $2000...  (wishful thinking).

Note: for many applications (e.g. graphics output routines) you don't need
high precision.  I wrote 4.5-digit precision routines for sin(), cos(), exp(),
log(), sqrt() and erf() that use table-lookup with linear interpolation.
(Each table is only 514 bytes long.)  They are written in 68000 AL and take
about 150 microsecs each (with no FP HW!) - faster than the VAX...

The VAX spent much less time in the cos() function than in the sin() because
(I guess) it just adds PI/2 to the argument and calls sin()...

- Moshe Braner