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From: mikem@uhccux.uhcc.hawaii.edu (Mike Morton)
Newsgroups: comp.sys.mac.programmer
Subject: questions on use of math chip by SE/30
Keywords: SE/30 68882 SANE precision
Message-ID: <3263@uhccux.uhcc.hawaii.edu>
Date: 14 Feb 89 18:28:07 GMT
Organization: University of Hawaii
Lines: 21


I'm curious about the use of the 68882 math chip by SANE in the SE/30.  I
believe that the older '881 chip has some admitted precision problems for
some functions (transcendentals?).  Apple, being the purists that they
are, didn't use the '881 to implement these particular functions, but
left the computation in software.

Does the '882 fix these inaccuracies?  If so, does SANE in the SE/30 use
the hardware for more operations?

On a related note, the March MacUser mentions a benchmark which runs much
more slowly on an SE/30 than a Mac IIx, and that "Apple's engineers were
mystified" as to why (p. 182).  Anyone know why?

 -- Mike Morton // P.O. Box 11378, Honolulu, HI  96828, (808) 676-6966 HST
      Internet: msm@ceta.ics.hawaii.edu
    (anagrams): Mr. Machine Tool; Ethical Mormon; Chosen Immortal; etc.

P.S. On the subject of SE hardware, note p. 180 of the same issue, with a
diagram listing the "Video ROM" -- but no corresponding number in the
picture.  Is this a joke or a funny typo?  [Presumably the Video ROM is
where the developer's pictures are hidden...]