[ntp:questions] Re: Windows timekeeping

Richard B. Gilbert rgilbert88 at comcast.net
Sat Aug 5 17:06:04 UTC 2006


Bryan Henderson wrote:
>>Windows assumes that the RTC on the motherboard is set to local time, as 
>>it would typically be set from someone's watch when it is first set up by 
>>an individual user (it may be set to Chinese or Taiwanese time when first 
>>delivered).
> 
> 
> I don't follow this part.  The user uses Windows to do this setting,
> right?  So Windows could choose any timezone for the hardware clock,
> and UTC would be a natural choice.  Windows obviously asks the new
> user what time zone he's in, and therefore when the user says what
> time his wristwatch says, Windows knows what UTC that corresponds to.
> 
> But I do believe that Windows systems still use local time, because I
> hear about people who run Linux and Windows on the same hardware and
> therefore Linux's 'hwclock' has to understand that the hardware clock
> is in some local time.
> 

The HARDWARE CLOCK knows nothing of time zones; it uses the time it was 
set to whether it was local time, or UTC.  The hardware clock is not the 
same as the system clock that Windows uses.  The hardware clock is 
battery operated CMOS logic and runs whether the system is powered on or 
not.  The system clock is a software/hardware construct with the 
software part belonging to Windows.  The hardware part "ticks" and the 
software part counts the ticks.  The system clock as I, and others, have 
said keeps UTC unless some idiot has totally botched the configuration 
of Windows (quite possible since the supply of idiots is inexhaustible).




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