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From: grr@cbmvax.cbm.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: 68881 in a 68010 Amiga (question)
Message-ID: <1003@cbmvax.cbmvax.cbm.UUCP>
Date: Tue, 18-Nov-86 08:31:13 EST
Article-I.D.: cbmvax.1003
Posted: Tue Nov 18 08:31:13 1986
Date-Received: Tue, 18-Nov-86 21:52:01 EST
References: <535@elmgate.UUCP>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 28
Keywords: Floating Point FPU 68881 68000 68010 Hardware

In article <535@elmgate.UUCP> jdg@elmgate.UUCP (Jeff Gortatowsky) writes:
>I've asked this before and never really got the response I was looking
>for (I only received one or two) so I thought I'd rephrase it and try 
>again.  Since a 68010 must emulate the coprocessor interface that a 68020
>has in microcode, it must read/write to addresses in memory that the
>881's registers are wired to (CIR,etc).  I would like to wire up such an
>interface as it's cheaper than any 020 modifications and should still be
>an improvement over software FP.
>
>I'm trying to use the Motorola guidelines for wiring an 881 to a 010. All
>I need to know is what address should the base register of the 881 be
>located at?  Is there an official space in the Amiga memory map for an 
>881 in such a configuration?  If not, where is a 'safe' place to put it?
>I don't want to conflict with other third party hardware I may add later
>if I can avoid it.  
>
>Jeff Gortatowsky       {allegra,seismo}!rochester!kodak!elmgate!jdg

As far as I know, the Amiga software only supports the 68881 when attached
to a 68020.  This makes your question essentially unanswerable.  There is
another Motorola application note that describes how to make a 68020 look
like a 68000, which is probably what the CSA board is based on in the
first place.

-- 
George Robbins - now working for,	uucp: {ihnp4|seismo|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)