Third serial port

[Timothy L. Kay]

I am having trouble installing a third serial port in my 386 running
ISC Unix/386.  I have the X5 update (new serial driver).  I have the
card set to IO address 3E8 (COM3), IRQ 2, and I have added appropriate
lines to /etc/conf/sdevice.d/asy and remade the kernel.

Unfortunately, I don't seem to be getting any interrupts from that
device.  All output seems to be at about one character per second,
which I would guess means that the driver is timing out.  No input
appears.

Does anybody know if it is possible to use IRQ 2 for a serial port?
Is it possible to share interrupts (can I put two ports on the same
interrupt and have it work)?

Thanks in advance,

Tim