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This Sunday morning, many of us will be setting our clocks ahead 1 hour for Daylight Savings Time.

What makes this different than last spring is that, thanks to the Energy Policy Act of 2005, Daylight Savings Time will start on the second Sunday in March (March 11, 2007) instead of the first Sunday in April (April 1, 2007).

Why is this a technology story? Most computer operating systems are programmed to know when Daylight Savings time is supposed to happen. That way they can update the system time and allow computers and applications to know what time it is, even after a time change.

Since the time change has now been rescheduled, many computer operating systems — along with PDA’s, Blackberries, cell phones and yes, even self correcting alarm clocks and VCR’s — won’t know to change times when Daylight Savings Time occurs this year.

Microsoft has issued a patch for Windows XP and Windows Server 2003, which should have installed on your computer already if you have been keeping up with your updates. If not, you can download it here. Windows Vista is not affected.

While there are no official updates for Windows 2000, Microsoft offers a tool that can be downloaded here which will walk you through updating Windows 2000 manually, as well as all versions of XP and Server 2003. There’s also a tool there to verify your version of Vista just in case.

For you Apple users, DST rule changes for the United States and most of Canada are already available in Mac OS X 10.4.5 or later. Apple is providing software updates for Mac OS X 10.3, 10.4 and later. To make sure that your clock maintains the proper time, simply install the updates that are shown for your computer in Software Update

Owners of devices that run Windows Mobile will also need to update their software. You can find instructions for that here. This includes devices like the Treo, T-Mobile Dash and any other Smart Phone devices that run the Windows Mobile Operating System.

Research in Motion has issued a patch for its BlackBerry devices available at this site, so if you use a BlackBerry you might want to check that out.

Java developers and those who maintain any type of Java based application should also be aware that this time change can affect the Java Runtime Environment as well. Sun outlines this on this web site.

There are no patches available for users of Microsoft Windows 95, Microsoft Windows 98, Microsoft Windows Second Edition, Microsoft Windows ME and Microsoft Windows NT 4. You will need to change your system clock manually and likely again if it auto-corrects when the time change is typically scheduled.

Owners of devices that run the Palm OS should consult the Palm OS site for any updates your device might require.

Other devices not listed here may be affected. Read this Wikipedia article for more details on affected systems.

If you have a device that you think might be affected, check with the manufacturer to verify.

It’s not the end of the world. The worst case scenarios tend to be computer calendar appointments being off by an hour but there could be more serious effects if certain automated processes fire off an hour later than they are supposed to.

Good luck! See you after the time change!

Jay Lee


Additional information from my friend Bob Entwhistle:

Additional information:

These folks have created unofficial patches for Win2K/NT/98/ME.

This article has a bunch of links to Linux/Unix patches.

Here’s the page for Mandriva that will guide you to their patches.

MandrivaUpdate downloads this automatically.

This command will indicate if you need a patch:
sudo zdump -v /etc/localtime | grep 2007

Here’s a guide for Ubuntu, presumably if you’re not automatically downloading updates. This should work for other Linuxes, also.

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