B-20 Appendix B: Feature Kits
7454-F072
RS-232 Port (Dual)
The Pentium III/Celeron Motherboard has two RS-232 ports (9-pin D-
shell connectors, Com 1 and 2) directly on the board. The Dual RS-232
Port Kit is used to make two additional ports (Com 3 and 4) available.
Ports 1 and 3 on the board can be supplied with +12 V DC on Pin 9
when properly set up in the BIOS. The total power drawn by Ports 1
and/or 3 must be within the limits of the capabilities of the power
supply.
Refer to the following table for RS-232 pinout information.
RS-232 DB-9 Male Connector Pinout
Pin Port A Port B
1 DCD DCD
2 RXD RXD
3 TXD TXD
4 DTR DTR
5 GND GND
6 DSR DSR
7 RTS RTS
8 CTS CTS
9 RI or +12* RI
* If Port 1 or 3 is powered, pin 9 will be +12 V.
The BIOS allows flexibility in mapping resources. However, a fully-
loaded system (2 PCMCIA cards that require IRQs, four serial ports in
use, USB in use, parallel port in use, and MSR) may not have enough
available IRQs to support all serial ports. Use a USB serial port
expander to overcome this PC architecture limitation.
Port 2 shares hardware resources with the IRDA connection; if IRDA is
in use, Port 3 is not available.
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