Configuring COM3 - xenix ignores me

[SPIESMAN, BILL]

I am having a problem configuring my compuer SCO xenix to use a third serial
port. I have tried a few recipes that I have found on the net, but I haven't had
much success yet. What I have is a basic IBM style I/O card which has
2 com ports and a printer port. I also have a modem which is configured
for com1. I use one serial port on the I/O card which is configured as
com2. I still have one serial port left (which is now configured as com3)
which I want to use.

My setup is thus:

    port        address        IRQ
---------------------------------
    com1        3f8             4
    com2        2f8             3
    com3        3e8             5

I have jumpered the IRQ5 line as it comes into the card to the
com3 port.

I then followed the net recipes, adding this line to sioconf.c:
{2,IBM_BOARD, 1,5,4, (sd)0x3e8,0,0,MCRBITS3},

and modifying the master file to include IRQ5 as a serial interrupt
by putting a 5 in the vec3 column of sio and incrementing vsiz to 3.
(I also set vsiz to 1 and removed IRQ5 from the pa line).


Now the recipe says that I'm done... but when I rebuild the kernel and
reboot, there are no new serial lines listed. In an attempt to see
if I was changing anything, I tried to break the serial ports by 
changing the entries in sioconf.c (changing the interrupt and/or
memory addresses). This HAD NO EFFECT! I realized that when xenix
boots that it might be reading the actual hardware configuration
from the BIOS and over-riding the entries in sioconf.c.

So I jumperd the I/O card so that com1 used IRQ3 and com2 used IRQ4,
changed the entried in sioconf.c to reflect this hardware change and
built/booted the new kernel. And what happened was.... the same
old thing. The boot message indicated that the two serial ports
are com1/irq4 and com2/irq3. Now the system flailed since the
interrupts were associated with the wrong ports, and I am left 
with the same problem; Xenix seems to be ignoring the changes I make
to sioconf.c. 

Has anybody dealt with this before?? Is there another step that
I have skipped??


HELP!!!

Bill Spiesman

spiesman at amarna.gsfc.nasa.gov