Technical Information 1-13I/O addresses and interrupt levels for the two channels are given Table Section 1-6. Theinterrupt level is selectable via Setup to either IRQ3 or IRQ4. Software selectable baseaddresses are 3F8h, 2F8h, 3E8h, and 2E8h.NOTE: Any interrupts used for the built-inserial ports are not available for ISA parallelports.Table Section 1-6 Serial Port Addressing and InterruptsStarting I/O Address Interrupt Level Port3F8h IRQ04 COM12F8h IRQ03 COM2*3E8h IRQ04 COM32E8h IRQ03 COM4* Used for IrDA data transferSee Section 2, “Setup and Operation”, for information on resetting the port through Setup.Serial interface specifications include:n Baud rate up to 19.2 KB per secondn Word length - 5, 6, 7, or 8 bitsn Stop bit - 1, 1.5, or 2 bitsn Start bit - 1 bitn Parity bit - 1 bit (odd parity or even parity).Serial interface signals are output through the system board’s 9-pin, D-subconnector. Theconnectors are located at the rear of the system unit. Pin locations for the serial interfaceconnector are shown in Appendix A.Infrared InterfaceThe I/O controller incorporates an infrared interface that provides two-way wirelesscommunication through the IR window (port) on the front of the system. The interface usesinfrared as the transmission medium instead of a traditional serial cable.
