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From: aburto@marlin.UUCP (Alfred A. Aburto)
Newsgroups: net.micro.amiga
Subject: Re: 68881 address in the Amiga
Message-ID: <663@marlin.UUCP>
Date: Tue, 28-Oct-86 11:06:04 EST
Article-I.D.: marlin.663
Posted: Tue Oct 28 11:06:04 1986
Date-Received: Tue, 28-Oct-86 23:25:49 EST
References: <533@elmgate.UUCP>
Reply-To: aburto@marlin.UUCP (Alfred A. Aburto)
Organization: Naval Ocean Systems Center, San Diego
Lines: 29
Keywords: floating point hardware 68881 CPU

In article <533@elmgate.UUCP> jdg@elmgate.UUCP writes:
>Does anyone know the memory address the 68881 is expected to be found at in
>the Amiga 68881 library?  Is there a standard address it should answer to?
>I 'd like to be able to use it with both Manx's next release any future
>CBM-Amiga releases.
>
>I've got an 881 and am going to try and mung up a board myself.  Is it
>basically as simple as the examples Motorola provides for wiring up an 881
>to an 010?  Any real pitfalls awaiting me?  Has anyone done this in a
>NON-COMMERCIAL product?  Any drawings your will to share?  Any special
>Amiga specific problems I should know about?  Any help would be welcome.
>I'll of course, make this info available to anyone who needs it.
>

As far as I know there is no 68881 library provided for the Amiga. C-A was
was working on one a while back but I think its been shelved for the time
being.
If you use the 68881 with a 68000 or 68010 then the 68881 is treated as a
peripheral. With the 68020 the 68881 is a co-processor and the floating
point instructions are programmed as for any other 68020 instruction.  This
is only my opinion but I think the best way to get the 68881 running on the
Amiga is to use 68020/68881 processor pair. 
I saw some articles in EDN from Motorola which listed MACROs you would to
write to get the 68881 to work with the 68000 or 68010. I don't remember
the issue though, but alot of the information you need is available in
articles published in EDN.