Serial Port Connectors; Parallel Port Connector; Figure B-3. Pin Numbers For The Serial Port Connectors; Table B-3. Pin Assignments For The Serial Port Connectors - Dell Precision 400 User Manual

These COM ports have the following I/O address
settings:
COM1: 3F8h
COM2: 2F8h
COM3: 3E8h
COM4: 2E8h
For example, if you add an internal modem card with a
port configured as COM1, the computer then sees logical
COM1 as the address on the modem card. It automati-
cally remaps the built-in serial port that was designated
as COM1 to COM3, which shares the COM1 IRQ set-
ting. (Note that when you have two COM ports sharing
an IRQ setting, you can use either port as necessary but
you may not be able to use them both at the same time.) If you
install one or more expansion cards with serial ports des-
ignated as COM1 and COM3, the corresponding built-in
serial port is disabled, as described in "Serial Port 1 and
Serial Port 2" in Chapter 3.
Before adding a card that remaps the COM ports, check
the documentation that accompanied your software to
make sure that the software can be mapped to the new
COM port designation.
To avoid autoconfiguration, you may be able to reset
jumpers or switches on the expansion card so that its port
designation changes to the next available COM number,
leaving the designation for the built-in port as is. Alterna-
tively, you can disable the built-in ports through the
System Setup program. The documentation for your
expansion card should provide the card's default I/O
address and allowable IRQ settings. It should also pro-
vide instructions for readdressing the port and changing
the IRQ setting if necessary.
For general information on how your operating system
handles serial and parallel ports as well as for more
detailed command procedures, see your operating system
documentation.

Serial Port Connectors

If you reconfigure your hardware, you may need pin
number and signal information for the serial port connec-
tors. Figure B-3 illustrates the pin numbers for the serial
port connectors, and Table B-3 lists and defines the pin
assignments and interface signals for the serial port
connectors.
B-6 Dell Workstation Midsize Systems User's Guide
1
6
Figure B-3. Pin Numbers for the Serial Port
Connectors
Table B-3. Pin Assignments for the Serial Port
Connectors
Pin Signal I/O
1 DCD I
2 SIN I
3 SOUT O
4 DTR O
5 GND N/A
6 DSR I
7 RTS O
8 CTS I
9 RI I
Shell N/A N/A

Parallel Port Connector

If you reconfigure your hardware, you may need pin
number and signal information for the parallel port con-
nector. Figure B-4 illustrates the pin numbers for the
parallel port connector, and Table B-4 lists and defines
the pin assignments and interface signals for the parallel
port connector.
5
9
Definition
Data carrier detect
Serial input
Serial output
Data terminal ready
Signal ground
Data set ready
Request to send
Clear to send
Ring indicator
Chassis ground