Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!caen!umich!sharkey!fmsrl7!wdl1.wdl.loral.com!wdl1!engle
From: engle@wdl1.wdl.loral.com (David Engle)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Comm ports
Message-ID: <1991Apr11.161906.23360@wdl1.wdl.loral.com>
Date: 11 Apr 91 16:19:06 GMT
Sender: news@wdl1.wdl.loral.com
Distribution: na
Organization: Loral Western Development Labs
Lines: 38
Originator: engle@wdl1

I have a shortage of COM ports on my 386SX system.  I'd like to ask
the net's help to see if I can "fix" the problem.

The system: 386SX-16, Award Bios V3.11, C&T chip set, SVGA, etc.,
running DOS 4.01 (and on occasion Windows3).

The problem is I need three fully functional, separate com ports.
The "normal" approach seems to be to assign the IRQ for com1 to
com3 when com3 is present, with the expectation that the two comm
ports will share the IRQ.  Com1 is where my mouse is and Windows
will not allow me to multiplex that IRQ.  I have also tried sharing
com2 and com4 on the same IRQ and that does not work either.

I have tried to utilize an IRQ normally utilized by LPT for com3
and I have tried to utilize IRQ2 (which is the chained expansion
interrupt for AT class PCs).  Neither of these approaches works.

It appears that the problem is in the driver assignments to the
IRQ addresses.  That is, my PC expects comm interrupts only on the
"normal" comm IRQs, any attempt to fool it fails.  An individual
I know says that a more recent version of the BIOS will allow multiple
non-shared comm ports.  This guy's advice is somewhat suspect, as he
has trouble figuring out the on-off switch.

So....Is what I need a new BIOS chip set? Or does anybody know of any
ather approaches that will work?

A rational alternative could be to get a bus mouse (thus freeing up
my 2nd comm port).  However, I need to know that I can assign its IRQ
to someplace out of the way (like a printer IRQ).  Can anybody tell me
what bus mouse you have and what IRQ range it (by product) can be set to?

Thanks in advance, Dave               engle@wdl1.wdl.loral.com

-- 
David Engle, KE6ZE - engle@wdl1.wdl.loral.com - 408/473-4419 @ work 
Facts, what facts?  I don't got to show you no stinking facts.  
These are opinions expressed here.