Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!mailrus!csd4.milw.wisc.edu!bbn!rochester!pt.cs.cmu.edu!andrew.cmu.edu!rg20+
From: rg20+@andrew.cmu.edu (Rick Francis Golembiewski)
Newsgroups: comp.sys.amiga
Subject: Re: 68881 and the PA
Message-ID: <IXkgTQy00WB985OF1Y@andrew.cmu.edu>
Date: 5 Jan 89 01:41:48 GMT
References: <6180@louie.udel.EDU>
Organization: Carnegie Mellon
Lines: 21
In-Reply-To: <6180@louie.udel.EDU>

>Only for those applications for which the need for Double Precision
>is more important than the need for speed or compatibility.
>For Single Precision applications, FFP is still faster, math chip or no.
>And everyone has FFP.
>Post a Whetstone rating for the PA and I might change my mind.

For basic (ie addition, subtraction, multiplication, etc. ) functions
the speeds of FFP and IEE (with 68881) are about the same, however I
tried comparing transcendental (ie ln, sin, cos, etc.) functions with
and without the 68881, [I was using StarBoard II multi-function module
with a preferial device {basically the same system that PA uses} 68881
at 12 Mhz ]  the 68881 was nearly 30 TIMES faster (and with a 68020
it would be faster still...), plus you get the extra double
precision.  So if you have an application that does a lot of Trig,
then it would definately help to support the '881.

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