B-6 Dell Workstation Mini Tower Systems User’s GuideThese COM ports have the following I/O addresssettings:COM1: 3F8hCOM2: 2F8hCOM3: 3E8hCOM4: 2E8hFor example, if you add an internal modem card with aport configured as COM1, the computer then sees logicalCOM1 as the address on the modem card. It automati-cally remaps the built-in serial port that was designatedas COM1 to COM3, which shares the COM1 IRQ set-ting. (Note that when you have two COM ports sharingan IRQ setting, you can use either port as necessary butyou may not be able to use them both at the same time.) If youinstall one or more expansion cards with serial ports des-ignated as COM1 and COM3, the corresponding built-inserial port is disabled, as described in “Serial Port 1 andSerial Port 2” in Chapter 3.Before adding a card that remaps the COM ports, checkthe documentation that accompanied your software tomake sure that the software can be mapped to the newCOM port designation.To avoid autoconfiguration, you may be able to resetjumpers or switches on the expansion card so that its portdesignation 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 theSystem Setup program. The documentation for yourexpansion card should provide the card’s default I/Oaddress and allowable IRQ settings. It should also pro-vide instructions for readdressing the port and changingthe IRQ setting if necessary.For general information on how your operating systemhandles serial and parallel ports as well as for moredetailed command procedures, see your operating systemdocumentation.Serial Port ConnectorsIf you reconfigure your hardware, you may need pinnumber and signal information for the serial port connec-tors. Figure B-3 illustrates the pin numbers for the serialport connectors, and Table B-3 lists and defines the pinassignments and interface signals for the serial portconnectors.Figure B-3. Pin Numbers for the Serial PortConnectorsParallel Port ConnectorIf you reconfigure your hardware, you may need pinnumber and signal information for the parallel port con-nector. Figure B-4 illustrates the pin numbers for theparallel port connector, and Table B-4 lists and definesthe pin assignments and interface signals for the parallelport connector.Table B-3. Pin Assignments for the Serial PortConnectorsPin Signal I/O Definition1 DCD I Data carrier detect2 SIN I Serial input3 SOUT O Serial output4 DTR O Data terminal ready5 GND N/A Signal ground6 DSR I Data set ready7 RTS O Request to send8 CTS I Clear to send9 RI I Ring indicatorShell N/A N/A Chassis ground1 56 9
