following advice from Mr. Bouyer and Mr. Drochner, i changed function
com_isapnp_match() in /sys/dev/isapnp/com_isapnp.c. i did not see
dev/isapnp/isapnpdevs. i guess my kernel source (7-19-98) is not quite
up to date. i recompiled the kernel. the boot process stopped upon
detecting COM2. the message says:

com2 at isapnp port 0x201/1: ns 8250 or ns 16450, ns fifo
panic: intr_establish: bogus irq or type
stopped at debugger +0x4: leave

after seeing this, i changed the port to 0x201 in the config file. i
also changed the irq number to one that was working fine with another
device. i got the same problem after rebuild and reboot. com0 and com1
are both detected as 16550a and configured correctly. i don't know how
to use GDB.  i'll download the most recent kernel source and try this
again. meanwhile, if anybody knows what the problem is, please help.
appreciated.