Technical Information 1-13
I/O addresses and interrupt levels for the two channels are given Table Section 1-6. The
interrupt level is selectable via Setup to either IRQ3 or IRQ4. Software selectable base
addresses are 3F8h, 2F8h, 3E8h, and 2E8h.
NOTE:
Any interrupts used for the built-in
serial ports are not available for ISA parallel
ports.
Table Section 1-6 Serial Port Addressing and Interrupts
Starting I/O Address
Interrupt Level
Port
3F8h
IRQ04
COM1
2F8h
IRQ03
COM2*
3E8h
IRQ04
COM3
2E8h
IRQ03
COM4
* Used for IrDA data transfer
See 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 second
n
Word length - 5, 6, 7, or 8 bits
n
Stop bit - 1, 1.5, or 2 bits
n
Start bit - 1 bit
n
Parity bit - 1 bit (odd parity or even parity).
Serial interface signals are output through the system board’s 9-pin, D-subconnector. The
connectors are located at the rear of the system unit. Pin locations for the serial interface
connector are shown in Appendix A.
Infrared Interface
The I/O controller incorporates an infrared interface that provides two-way wireless
communication through the IR window (port) on the front of the system. The interface uses
infrared as the transmission medium instead of a traditional serial cable.
