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Chapter 2: 7401-4xxx Product Overview 2-11
Serial Ports
The 7401-4xxx Celeron/Pentium III processor board provides two RS-
232 ports (9-pin D-shell connectors, Ports 1 and 2) directly on the board
and supports two additional RS-232 ports. Ports 3 and 4 require an
optional harness connection to the board. Ports 1 and 3 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
pin-out information.
The BIOS permits 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.
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*
VDC
RI
* If Port 1 or 3 are powered, pin 9 will be +12 V.