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From: kds@intelca.UUCP (Ken Shoemaker)
Newsgroups: net.micro.68k
Subject: Re: Re: Sun-3 floating point
Message-ID: <151@intelca.UUCP>
Date: Thu, 12-Dec-85 16:03:56 EST
Article-I.D.: intelca.151
Posted: Thu Dec 12 16:03:56 1985
Date-Received: Sat, 14-Dec-85 23:22:37 EST
References: <196@gould9.UUCP> <691@aimmi.UUCP>
Organization: Intel, Santa Clara, Ca.
Lines: 19

> Yes - as I understand it, the SUN software checks for the FPA board at
> boot time. If it's there, it ships stuff over the fast local bus to the
> FPA instead of the 68881 chip.
> The clever bit is that the FPA doesn't need to emulate the 68881 - in certain
> out-of-range cases, the FPA board gives up in disgust, so the CPU passes the

I would think that there are still some problems with this, with respect to
round-off models, but oh well...Can anyone explain to me how this works?
If the FPA board is there, does the 68020 trap on every floating point
op and ship the stuff over by hand, or is there something in the coprocessor
interface that the startup code sets to make the 020 use the FPA rather than
the 881?  As they say, pardon my ignorance...
--
yes, some uncomplicated peoples still believe this myth...

Ken Shoemaker, Santa Clara, Ca.
{pur-ee,hplabs,amd,scgvaxd,dual,qantel}!intelca!kds
     
---the above views are personal.