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From: dillon@CORY.BERKELEY.EDU (Matt Dillon)
Newsgroups: comp.sys.amiga
Subject: Re: Questions about M68881 FPU
Message-ID: <8709180202.AA07941@cory.Berkeley.EDU>
Date: Thu, 17-Sep-87 22:02:09 EDT
Article-I.D.: cory.8709180202.AA07941
Posted: Thu Sep 17 22:02:09 1987
Date-Received: Sat, 19-Sep-87 18:27:09 EDT
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>	  be used?  Meaning -- can I use floating point opcodes as if it
>	  was a regular command?

	Not with a 68000.  It *is* possible to write a trap handler for the
illegal instruction, but it would be extremely slow.  Only a 68020 supports
co-processors with actual machine instructions.  I.E. the co-processor must
be mapped for a 68000/10 to be able to use it.

>	- What is the form of BCD floating point?

	No idea.

>	- How would you convert from floating point to ASCII and back?

	No specifics.  Assuming you have the IEEE floating point format
	reference it would be a simple matter to write a small subroutine
	to do it.  The question seems slightly out of place.

>	- Why should I use the libraries rather than address it directly?
>Those are some starting questions but please tell me as much as you think
>is meaningful.  Also, if you have any examples you could send I would 
>apreciate it.

	I assume the support library handles multi-tasking compatibility
to some degree (or is this handled by the OS???).  That Aside, there is
another very good reason to use the library rather than access the chip
directly:  It means you can run your program on any Amiga, with or without 
a 68881.

					-Matt