Sun VMEbus question

[Steve Barber]

I have a Sun 4/110 (3-slot 9U VME bus) and recently ran across a VME-SIO
board for a price that I couldn't refuse.  This is a 6U size board with 4
serial ports using 2 Mostek 8337 (if I remember right) serial chips.  It's
made by United Technologies, and puts the RS-232 signals onto the P2
connector of the VME bus (columns A and C of that connector).  There's a
separate connector board which is essentially a ribbon cable that plugs
into the P2 bus and runs directly to 4 DB-25 connectors.  All of the
RS-232 signals are placed in the USER DEFINED pins of the P2 connector.
My main question is, does the Sun 4 CPU board use these pins for anything
else.  I want to make sure of this before I even plug the board in since
RS-232 drivers would probably do nasty things to something that wasn't
expecting it.

Secondly, this is a 3-slot bus and the CPU board is double-height.  The
serial board is going to take up the last slot, but is there any reason
the I/O panel connector can't plug in to the P2 connector between the two
boards?  There should be room for it physically, though I haven't looked
yet.  When I install this equipment, will I need to mess with any of the
backplane jumpers?

Finally, from the software point of view:  I'm running SunOS 4.1, and it
sounds like I want to write a STREAMS driver for this board.  I've been
RTFMing a lot but still don't have a good handle on what I actually need
to do.  Has anyone written a STREAMS driver for a serial board that I
could look at?  My goal is to make these ports look just like the ports on
the CPU board, and it sounds like I can push the ldterm(4) and ttcompat(4)
STREAMS modules onto some kind of a driver and get most of it without too
much work.  Basically I'm looking for examples.

Thanks for any help you can provide.  Please respond by mail and I'll
summarize if there's any interest - I have a limited news feed, and
generally these groups aren't part of it.

Steve Barber  [steveb at ombrage.mi.org]