Dell Latitude C840 - Manual (Page 8)

When you receive your computer, the infrared sensor is disabled. You can use the system setup program to enable the infrared sensor. For information on
transferring data, see Windows Help , the Windows Help and Support Center , or the documentation that came with your infrared-compatible device.
PC Card Slot — Has two connectors that support various types of PC Cards, including modems and network adapters. For more information, see " Using PC
Cards ."
IEEE 1394 Connector — Use this connector to attach devices supporting IEEE 1394 high-speed transfer rates, such as some digital cameras and video
cameras.
Audio Connectors
Attach a microphone to the connector.
Attach headphones or speakers to the connector.
Attach record/playback devices such as cassette players and CD players to the connector.
Air Vents — The computer uses an internal fan to create airflow through the vents, which prevents the computer from overheating.
Back View
NOTE: The computer turns on the fans when the computer gets hot. The fans may make noise, which is normal and does not indicate a problem with
the fan or the computer.
CAUTION: Do not push objects into the air vents or openings of your computer. Doing so can cause fire or electric shock by shorting out interior
components.