Two (2) 9-pin RS-232 serial ports.. PCI Express x1 interface (will also work on PCI-E x4, x8, x16 slot).. Compliant with PCI Express specification Revision 1.1.. PCI Express single-lane (x1) bus bandwidth 2.5 Gbps.. Support DOS, Windows 98 / Me / NT 4.0 / 2000 / XP / Vista / Win7 / Win8 / Server 2003 & 2008 / Linux operating systems.