Technical Information 1-27
Serial Interface
The system has two standard serial ports. The serial ports support the standard RS-232C
interface. The interrupt is selectable via Setup. 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 B
Each of the two serial ports can be configured as COM1, COM2, COM3, or COM4. The
options for the base address and interrupt request that can be selected are provided in Table
Section 1-8. The primary serial port (P3) defaults to COM1, IRQ3. The secondary serial
port defaults to COM2, IRQ4. Note that the I/O controller supports the mapping of any of
these logical ports to either physical port. Additionally, each serial port can be
independently disabled. It is the responsibility of the system BIOS to ensure that the base
address or interrupt request line used by a serial port is not used by the EISA bus (or
conflicts will result).
Table Section 1-8 Serial Port Addressing and Interrupts
Base I/O Address
for Serial #1
Interrupt Request for
Serial #1
3F8H (default)
IRQ04 (default) or 10
2F8H
IRQ03 or 11
3E8H
IRQ4 or 10
2E8H
IRQ3 or 11
Base I/O Address
for Serial #2
Interrupt Request for
Serial #2
2F8H
IRQ3 (default) or 11
3F8H
IRQ 4 or 10
3E8H
IRQ 4 or 10
2E8H
IRQ 3 or 11
*Default for serial port
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).