>Sorry for interrup again,my question is that how to assign the IRQ and I/O
>to my ISA modem?For example in Enthernet card,I can use "insmod ether=eth0
>irq=3 io=0x200 " to assign the IRQ and I/O but I know which
>command can help me to do like this for isa modem.

Alright, if you do not have program to change your card's resource
configurations, please try (no guaranty):
1, Find out your modem's settings, for instant: io=0x2e0 irq=10

2, backup your device:
    mv /dev/ttyS0 /dev/ttyS0
**Ps, I am sorry, I should suggest you to use 'ttySXX' instead of 'cuaXX'.
Therefore I will use ttySXX in my example from now on. ^_^

2, make nod:
mknod -m 660 /dev/ttyS0 c 4 64 # 0x2e0

3, link your modem
ln -sf /dev/ttyS0 /dev/modem