The ICOP-1800 works fine on Windows NT 4.0, please ensure your customers
reserved IRQ 5 for ICOP-1800.
, and add new serial ports in control panel.

 

Example in AMI BIOS

If your ICOP-1800 is set the IRQ to 5 (Factory default)

1.       In COMS setup, please check the ”uPNP/PCI configuration”v section, 
IRQ 5 must be reserve for ISA/EISA.
Do not select ”uPCI/PNP”v in the option.

2.       Please check other non-PNP device is not using IRQ 5.

3.       Start Windows NT 4.0, go to ”uSetting”v ”¼ ”uControl Panel”v ”¼ ”uCOM”v

Then ”uAdd”v 4 COM ports, and please taking notice about the port address, 1st 
is ”u280”v, 2nd is ”u288”v, 3rd is ”u290”v, 4th is ”u298”v and the IRQ of all of
them are ”u5”v.

4.       Restart your Windows NT 4.0, and ICOP-1800 should be work with your 
Windows NT 4.0

 

I setup a new Windows NT 4.0 today, and install an ICOP-1800 to test the flow 
above.
After install complete, I connect a modem to ICOP-1800”zs COM 1, and modem found
by Windows NT 4.0

 

PS. In some systems IRQ 5 may used by Parallel Port (Print Port) or Audio 
Device.