HP Compaq Presario CQ42-210AU Notebook PC - Manual (Page 19)

Bottom components
Component Description
(1) Battery bay Holds the battery.
(2) Battery release latch Releases the battery from the battery bay.
(3) Vents (4) Enable airflow to cool internal components.
NOTE: The computer fan starts up automatically to cool
internal components and prevent overheating. It is normal
for the internal fan to cycle on and off during routine
operation.
(4) Memory module compartment Contains 2 memory module slots and, on select models, the
wireless LAN (WLAN) device.
CAUTION: To prevent an unresponsive system, replace
the wireless module only with a wireless module authorized
for use in the computer by the governmental agency that
regulates wireless devices in your country or region. If you
replace the module and then receive a warning message,
remove the module to restore computer functionality, and
then contact technical support through Help and Support.
(5) Hard drive bay Holds the hard drive.
Components 9