2-10 Dell OptiPlex E1 Managed PC Reference and Installation Guide6HULDO 3RUW DQG 6HULDO 3RUW Serial Port 1 and Serial Port 2 configure the system’s built-in serial ports. These cate-gories can be set to Auto (the default option) to automatically configure a port, to aparticular designation (COM1 or COM3 for Serial Port 1; COM2 or COM4 for SerialPort 2), or to Off to disable the port.If you set a serial port to Auto and add an expansion card containing a port configuredto the same designation, the system automatically remaps the built-in port to the nextavailable port designation that shares the same IRQ setting as follows:á COM1 (input/output [I/O] address 3F8h), which shares IRQ4 with COM3, isremapped to COM3 (I/O address 3E8h).á Likewise, COM2 (I/O address 2F8h), which shares IRQ3 with COM4, isremapped to COM4 (I/O address 2E8h).NOTES: When two COM ports share an IRQ setting, you can use either port as nec-essary, but you may not be able to use them both at the same time. If the secondport (COM3 or COM4) is also in use, the built-in port is turned off.If you are using the Microsoft Windows 95 or IBM OS/2 operating system, you cannotuse both serial ports at the same time.For more information about built-in ports, port designations, IRQs, and the remappingof ports, see “Connecting External Devices” in your onlineSystem User’s Guide.3DUDOOHO 3RUWParallel Port configures the system’s built-in parallel port. This category can be set to378h (the default setting), to alternate addresses 278h or 3BCh, or to Off to disablethe port.NOTE: Do not set Parallel Port to 278h if you have an Enhanced Capabilities Port (ECP)device connected to the port.3DUDOOHO 3RUW 0RGHParallel Port Mode controls whether the system’s built-in parallel port acts as an AT-compatible (unidirectional) or PS/2-compatible (bidirectional) port.Your system also supports ECP mode, which can be used by Windows 95.Windows 95 uses ECP protocol automatically if it detects an ECP-capable device,eliminating the need for an ECP option in this category.Set this category according to the type of peripheral device connected to the parallelport. To determine the correct mode to use, see the documentation that came withthe device.,'( 'ULYH ,QWHUIDFHIDE Drive Interface enables or disables the system’s built-in EIDE hard-disk driveinterface.