Compaq 247320-003 - Deskpro 4000 - 5166 Model 2500/CDS Reference Manual page 227

G
appendix
When your computer no longer automatically displays the
correct date and time, it may mean the battery providing power
to the real-time clock needs to be replaced. Battery life is
usually about five years. Before replacing the battery in a
personal computer, perform the steps in "Recording Hard Drive
Parameters" and "Preparing the Computer for Installation."
Computer Setup automatically detects and configures most
Compaq components, including Compaq hard drives. If the
machine you are servicing has a Compaq hard drive, go to the
next section, "Preparing the Computer for Installation."
If the computer being serviced has a third-party hard drive, you
must complete the following steps before installing the battery:
1. Run Computer Setup and record the drive type displayed in
the System Configuration Summary.
2. If the drive type number is 65 or 66, record the drive
parameters.
Drives with these designators are user-defined types, also
called soft-drive types. Whenever the nonvolatile memory
(CMOS) has become invalid, such as after the installation
of a new battery, drive parameters must be entered
manually for these user-defined drives.
3. After you have completed the battery installation, run
Computer Setup and use the drive table parameters
recorded earlier to reconfigure the system.
Drive parameters must be reentered after battery
installation in order to reconfigure the hard drive. The
hard drive is inoperable until this is done.