Dell Inspiron 7500 System Reference Manual page 92

NOTE: Make sure that there are no books, papers, or other objects between the two infrared devices and that the two devices are within
the 30° cone.
Modem Port
The Modem Port option appears only if your computer has an integrated modem. This option allows you to map the address of the port to avoid
address conflicts with other devices.
When this option is set to Customized (the default), the base I/O address/interrupt request (IRQ) is 2F8 IRQ3, the configuration port is 130, and
the 16-bit direct memory access (DMA) channel is DMA 6.
Set Modem Port to Off if you want to disable the port and free its assigned address for another device. When this option is set to Auto, the
operating system or the basic input/output system (BIOS) configures the port automatically.
USB Connector
Use the Universal Serial Bus (USB) connector (see Figure 3) to attach one or more USB devices, such as a mouse, to the computer. USB is a
peripheral bus standard that enables automatic detection of USB-compliant peripheral devices.
Figure 3. Pin Assignments for the USB Connector
Table 1. USB Connector Pin Assignments
Pin Signal
1 VCC
2 -Data
3 +Data
4 Ground
Serial Connector
Use the 9-pin serial connector (see Figure 4) to attach a serial device to the computer. The serial port passes data in serial format (1 bit at a time
over one line). This port supports a variety of devices, including a serial mouse, that require serial data transmission. If you reconfigure your
hardware, you may need pin number and signal information for the serial connector.
Figure 4. Pin Assignments for the Serial Connector
Definition
Cable power
N/A
N/A
Cable ground