NCR 7454, User Manual, Page: 32 / 244

1-12 Chapter 1: Product Overview
Serial Ports
The Celeron Motherboard provides two RS-232 ports (9-pin D-shell
connectors, Ports 1 and 2) directly on the Motherboard and supports
two additional RS-232 ports. Ports 3 and 4 require an optional harness
connection to the Motherboard. 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 pinout
information.
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.
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.