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From: aburto@marlin.NOSC.MIL (Alfred A. Aburto)
Newsgroups: comp.arch
Subject: Re: 68040 where is it?
Message-ID: <1477@marlin.NOSC.MIL>
Date: 10 Sep 90 18:51:42 GMT
Reply-To: aburto@marlin.nosc.mil.UUCP (Alfred A. Aburto)
Distribution: comp.arc
Organization: Naval Ocean Systems Center, San Diego
Lines: 26

In article <14263@cbmvax.commodore.com> daveh@cbmvax (Dave Haynie) writes:
In article <CHUCK.PHILLIPS.90Aug25143508@halley.FtCollins.NCR.COM> writes:

>>Also, with the 040 trapping, then executing software routines for
>>trancendental functions, I'd _expect_ at least the trancendentals to be
>>computed slower than a Weitek or 882, in spite of the PR.

>Why is that?  Weitek's don't have built-in trancendentals, either.  In
>
>Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"

Dave,
The Weitek has other advantages over the 68040.  No doubt the Weitek uses
64-bit (or there abouts) registers for general purpose operations such
binary arithmetic shifts and adds.  These types of operations are necessary
for example in using the CORDIC algorithm to approximate sin, cos, sincos,
exp, log, asin, acos, atan, sinh, and cosh.  The 040 is limited to 32-bit
binary shifts and adds. 

I got a feeling Dave that the 040 will do the transcendental functions with
ieeesp (32-bit) real fast (probably quicker and just as accurate as the 68882
at the same clock), but the ieeedp (64-bits) is going to require a bit of
igenuity (magic) me thinks.  Just my opinion at this time.....

Al Aburto
aburto@marlin.nosc.mil