How Windows keeps track of the date and time (232488)


The information in this article applies to:

  • Microsoft Windows NT Server 4.0
  • Microsoft Windows NT Workstation 4.0
This article was previously published under Q232488

SUMMARY

This article describes how Windows keeps track of the date and time.

MORE INFORMATION

When you start Windows, it gains direct access to the memory of the Real Time Clock (RTC) and uses its date and time values to set the computer date and time. Timer interrupts maintain the computer time when Windows is running. A Time Daemon in Windows runs approximately once each hour after the Windows starts. The Time Daemon compares the time in Windows with the time in the RTC. If the two times are more than one minute apart, Windows changes the time and date to match the RTC. You cannot change the time interval for the Time Daemon to run.

If you use a time synchronizing service, such as the TimeServ.exe tool included with the Windows NT 4.0 Resource Kit, the tool updates the time in Windows and the computer's RTC.
If the Windows Time Service runs on a Windows 2000 based-computer, the Time Daemon in Windows cannot run approximately one time each hour after the Windows starts.

REFERENCES

For more information, visit the following Microsoft MSDN Web sites:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/setlocaltime.asphttp://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/setsystemtime.asp

Modification Type:MajorLast Reviewed:5/23/2006
Keywords:kbHardware kbinfo KB232488
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