We have an OpenServer 5.0.0 system that has an external modem on COM1 (to allow remote support dial-in). COM2 is wired to a dot matrix printer. We need to add an additional serial dot matrix printer. I think the SCO handbook says you can't add an additional card that would use COM3/4 as these use the same interrupts as COM1/2. Is there a simple/cheap way to add this printer without buying some sort of Digi box?