[comp.sys.sun] Floating point questions and answers

dgh@sun.com (David Hough) (04/24/89)

> We don't seem to have [FPPG Addendum], are copies available from our
> local sales office?

I think almost all Sun manuals can be ordered at about $10 per.  A sales
office should have a list of available items.  However if you have SunOS
4.0 for Sun-3 or Sun-4 then you definitely have the Addendum somewhere in
your document crate.  Find the Programmer's Guides Minibox, then the READ
THIS FIRST in that box.  It is mostly the Addendum you are looking for.

> Is there a canonical software library to make a Fujitsu
> MB86911 have the same functionality as the Sun FPA board?

The Sun-3 FPA is a (full size) board, the Sun-4 FPU is a set of three
chips, the new Sun-4 FPU2 is a set of two chips on a small daughter board.
The Sun-3 FPA is microcoded with a number of CISC instructions like
elementary transcendental functions and some graphics primitives.  When
exceptions arise they are recomputed by software that uses the MC 68881.

The Sun-4 is a RISC that implements just the SPARC architecture and it's
definitely not microcoded.  When programming in C or Fortran, however, the
differences between Sun-3 FPA and Sun-4 will not be too noticeable except
in the transcendental functions.  The FPA microcode is more or less frozen
for all time since there isn't room for any more, while the Sun-4
elementary transcendental functions improve in accuracy and performance
over time.