Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!husc6!ogccse!cvedc!nosun!tektronix!psueea!parsely!agora!billsey
From: billsey@agora.UUCP (Bill Seymour)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Do Amiga libraries support 68000/68881?
Message-ID: <1619@agora.UUCP>
Date: 29 Aug 89 02:10:17 GMT
References: <2613@trantor.harris-atd.com:
Organization: Advanced Solutions, Hillsboro, OR
Lines: 34

From article <2613@trantor.harris-atd.com:, by laprade@ringworld.harris-atd.com (Ken Laprade):
: This is mentioned in the README file of the LUCAS distribution:
: 	It should be noted that when the 68020-68881 pair is 
: 	installed the new IEEE math libraries which support the 
: 	68881 are used for floating-point transparently.
: 
: Do the new IEEE math libraries also support the use of a 68000-68881
: combination?  If so, what address must the 68881 be located at (there
: is no coprocessor space in the 68000)?  Does the Amiga check for a
: 68881 automatically on bootup?  If not, what is required to tell it
: there is one there?

	For the 68000/68881 combo you need to have a math_resource set up
with the base address for the 68881. When the IEEE libraries are invoked,
and they don't see a 680(2|3)0/6888(1|2) combo, they look for this resource.
If they don't find the resource, then they go into software emulation mode.
Note that the 68000/68881 support via the 1.3 IEEE libraries is pretty non-
optimal. You don't get major speed improvements for many applications. (I
have seen a mandelbrot generator optimised for 68000/68881 that was running
close to 300 times faster than with the IEEE libraries... and 1200 times the
speed of 68000 alone... But then he'd really done a lot to optimise for his
combo! (68000 at 14.32 MHz, 68881 at 20MHz.))

: Thanks for any help.
: 
: -- 
: Ken Laprade			ARPA: laprade@trantor.harris-atd.com
: Harris Corporation - GISD	UUCP: ...uunet!x102a!trantor!laprade
: Palm Bay, Florida		voice: (407)727-4433
-- 
     -Bill Seymour             ...tektronix!reed!percival!agora!billsey
                               ...tektronix!sequent.UUCP!calvin!billsey
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