there are four universal serial bus (usb) v2.0 connectors, two on the front of the computer and two on the rear of the computer. use the usb connectors to connect optional telephony and multimedia devices. usb 2.0 technology transfers data at up to 480 megabits per second (mbps) with a maximum of 127 external devices and a maximum signal distance of 5 meters (16 ft) per segment (if the device that is attached to the computer is a usb 2.0 device). if the computer has multiple usb devices attached to it, the usb hub must be usb 2.0, otherwise, all usb 2.0 devices will transfer data at 12 mbps. using plug and play technology, usb devices are configured automatically. the following illustration shows a usb connector.

   

    use a 4-pin usb cable to connect external devices to usb connectors.

    if you connect a ps/2 (non-usb) keyboard to the keyboard connector, usb ports and devices are disabled during power-on self-test (post).

    if you connect a usb keyboard that has a mouse port, the keyboard emulates a mouse, and you cannot disable the mouse settings in the configuration/setup utility program.