Subject: Re: Sun3 hardware questions.
To: Julian Bean <>
From: J.T. Conklin <>
List: port-sun3
Date: 04/02/1996 10:57:07
>> I am now (officially) the proud owner of a Sun3/260 (w/a cgtwo).
>> Being so inclined, I yanked out the cpu board to have a look.  The
>> system has a 68020 at 25 Mhz and a 68881 at 20 Mhz.  This seems to
>> jive with the fact that a 50 Mhz and a 40 Mhz crystal are right
>> nearby (what the 200Mhz crystal a way over yonder controls, I don't
>> know).
>> Looking at this, I wondered two things:
>> 1. Can I put a 68882 in place of the 68881 (and would this be worth it)?

> I don't think so.  They have a different pinout... at least, the
> ones I have do.

That's odd.  

The Sun 3 Archive web pages ( say
that the 882 is pin and command compatible with the 881, and is a
suitable upgrade.  I vaugely remember the 881/882 manual saying the
same, but I can't check as it's at home right now.

If you replace a 881 with an 882, I wouldn't expect much of a
performance improvement.  To win you need to unroll loops and
re-arrange fmove instructions, which gcc doesn't do right now.