06-24-2013 11:56 AM
The HP 9000 B2600 workstation does not have a BIOS per se, but rather what is called a Boot Console Handler. This 'BCH' is the firmware interface for the system allowing changes to boot paths, boot behavior, time of day, etc, etc.
It should not realy be compared to what you may think of as a PC's BIOS since this is not a PC but a UNIX workstation designed to run HP-UX (versions 11.11, 11.00 and 10.20 more specifically).
There is a battery that protects the contents of certain variables such as boot device settings and time of day (although this may have been handled by its own RTC chip with its own battery - not certain there).
06-26-2013 09:21 AM
Well, basically the RTC chip simply keeps a consistent count by use of an oscillator. This count is translated to a time of day used by the system firmware. The OS reads this value from the firmware.
If the battery powering this chip starts to fail then the oscillator starts to oscillate at an inconsistent rate. This effects the count translation and then the time that is reported. Its this variance in the count cycle during a battery or RTC failure that explains why the time change can swing so wildly (from simply running slow to jumping around by many days, weeks or even years.
Hope that answers what you were looking for?