Toshiba U400 - Manual (Page 131)

User’s Manual 6-5
Power and Power-Up Modes
The charge in the RTC battery is getting low or has been exhausted. You
will need to set the date and time within the BIOS setup using the following
steps:
1. Press F2 key - the BIOS setup screen will be displayed.
2. Set the date in System Date.
3. Set the time in System Time.
4. Press F10 key. Confirmation message will appear.
Press Enter key. BIOS setup will terminate and the computer will be
rebooted.
After configuring the date and time it is recommended that you switch the
computer on and then leave it in this state so that the Real Time Clock
battery can be charged.