Dell Inspiron 3500 - Manual (Page 36)

External Keyboard, Keypad, or Mouse: Dell™ Inspiron™ 3500 Portable Computer
You can connect a keyboard with a standard PS/2 connector to the PS/2 connector on the computer, or a USB-compatible keyboard to the USB connector.
You can attach an external numeric keypad to the PS/2 connector on the computer, or a USB-compatible keypad to the USB connector.
You can attach a PS/2-compatible mouse to the PS/2 connector on the computer, or a USB-compatible mouse to the USB connector.
While an external mouse is attached to the computer, the touch pad is still usable.
The touch pad device drivers that Dell installed on your hard-disk drive work with a PS/2 mouse, serial mouse, or USB mouse from Dell. If you did not receive your
mouse from Dell, you must install device drivers separately to use the mouse. This software is usually included with mouse installation kits.
NOTE: You can still use the built-in keyboard when an external keyboard or external keypad is attached to the computer.
NOTE: Before connecting or disconnecting a serial mouse or PS/2 mouse, it is recommended that you turn off your computer.