On 11/29/06, Owen Heisler <owenh000@gmail.com> wrote:
With the regular GUIs in Windows (XP), I don't think it is possible to use BIOS UTC time... but maybe (probably) there is some very well hidden, badly named registry key that magically makes Windows read UTC time from the BIOS. If someone knows what it is, I'd be interested.
Well, I clicked "send" but then decided I may as well look around to see what I can find on the net via Google. It seems that there exists an undocumented registry key that tells Windows that the BIOS time is UTC. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal (REG_DWORD = 1) It seems Windows might do weird things with this setting, like assume still that the time is not UTC and then update for DST or NTP... but perhaps that can be circumvented by disabling both. There is mention of some other bugs too. Oh, and it seems that Windows Vista will not support BIOS UTC time either (or doesn't, I don't know or really even care if it has been released or not). Here are the links I found (the second is Google's cache; the real page wouldn't work for me): http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html http://216.239.51.104/search?q=cache:1pIggEd-0YUJ:dlgwiki.dot42.org/index.php/Allow_the_system_clock_to_be_set_in_UTC/GMT+http://dlgwiki.dot42.org/index.php/Allow_the_system_clock_to_be_set_in_UTC/GMT&hl=en&gl=us&ct=clnk&cd=1&client=firefox