How Windows Keeps Track of the Date and Time

• Microsoft Windows NT Server version 4.0
• Microsoft Windows NT Workstation version 4.0

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. This information contained in this article was obtained from the Windows Operating System Interactions with BIOS and Real Time Clock white paper, located at the following Microsoft Web site:

http://www.microsoft.com/technet/year2k/

Additional query words: time, RTC, BIOS

Keywords : kbhw kbtool
Version : winnt:4.0
Platform : winnt
Issue type : kbinfo