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From: seanf@sco.COM (Sean Fagan)
Newsgroups: comp.arch,comp.lang.fortran,comp.misc
Subject: Re: Quadruple-Precision Floating Point ?
Keywords: REAL*16 hardware
Message-ID: <1991@scolex>
Date: 1 Jan 89 05:00:38 GMT
References: <8561@alice.UUCP> <3688@s.cc.purdue.edu> <285@loligo.fsu.edu> <2334@tekcae.CAX.TEK.COM>
Reply-To: seanf@sco.COM (Sean Fagan)
Organization: The Santa Cruz Operation, Inc.
Lines: 22

In article <2334@tekcae.CAX.TEK.COM> kurtk@tekcae.CAX.TEK.COM (Kurt Krueger) writes:
>The new 180 series machines DO have a real full double precision (128 bit)
>machine instruction set for the four basic arithmetic ops.  The interesting
>thing is that running that machine in the 170 mode (with the FXi and DXi
>instructions) would slightly beat the machine in the 180 mode.  Which goes
>to show that the mere presence of 128 bit instructions doesn't automatically
>make for speed.
>RISC - Seymour was right!

Hold on a second.  A) Which model?  Performance in 170-state is different on
a 830 than on a 995E, so that could have something to do with it.  Also, how
about interrupts and what not?  In 180-state, you have to worry about page
faults, but not while in 170-state, and that could have something to do with
it.

Actually, I think the main advantage is that 170-state microcode is *much*
easier to deal with than 180-state microcode, and that could be it.

-- 
Sean Eric Fagan  | "Merry Christmas, drive carefully and have some great sex."
seanf@sco.UUCP   |     -- Art Hoppe
(408) 458-1422   | Any opinions expressed are my own, not my employers'.