HP 15 Maintenance And Service Manual page 147

This relates to clearing the Real Time Clock (RTC) CMOS memory that contains PC configuration data.
6. Does resetting the CMOS configuration memory return the PC back to factory defaults?
The process of resetting the CMOS will return certain system settings to factory default but will not
reset many of the system data and configuration defaults to their factory settings. To return these
system data and configuration defaults to factory settings, refer to question and answer 1 and follow
the instructions for returning the BIOS settings to factory defaults.
Questions and answers 139