2007 Daylight Savings Time Changes for PDAs

In 2005, the United States congress passed the Energy Policy Act of 2005, which among other things extended the duration of Daylight Savings Time in United States, starting in 2007. Canada and Bermuda have followed suit.

The problem is that, during the extended periods of three weeks in the spring and one week in the fall, many clocks on systems which automatically to change to and from Daylight Savings Time will continue to operate on Standard Time, even though Daylight Time is actually in effect. These uncorrected systems will not be synchronized with other systems which have been fixed.

This page tells you how to correct that, so that the automatic Daylight Time changes take place on the correct date.

We have until March 11, 2007 to fix this problem in the U.S. and Canada.

Windows CE Devices

Here is an unofficial patch: Edgeblog: Daylight Saving Time - Windows Mobile Fix

Earlier versions of Palm OS did not have a facility for automatically changing to Daylight Savings Time.

Tips for adjusting DST on PalmOS5.X

The Hewlett-Packard 100LX and 200LX Palmtop PCs are fully-programmable, MS-DOS based PDAs, which despite being over a decade old remain quite popular, with used units in good condition selling on Ebay for a premium price. A great many of these are in daily use, with new applications still being developed.

However, the rules for Daylight Time were different when these wonderful little machines were made. Here is how to correct that, so that the automatic Daylight Time changes take place on the correct date.

How to fix the 2007 Daylight Time dates

1. Using Filer, check to see if file C:\_DAT\TIMEZONE.DAT already exists. If it does, then some modification has already been made. Skip to Step 3.
2. If C:\_DAT\TIMEZONE.DAT does not exist, then copy file D:\_SYS\TIMEZONE.DAT to C:\_DAT\TIMEZONE.DAT. (You cannot modify file D:\_SYS\TIMEZONE.DAT directly because it is in ROM.)
3. Open the Memo program, and use it to edit file C:\_DAT\TIMEZONE.DAT.
4. If you have sections besides these, leave them alone. The order of sections is not important. The file should look something like this when you are done editing:

   European
   3:25-31  6 1:00  
   10:25-31 6 0:00  
   Northern
   3:8-14   6 1:00  
   11:1-7   6 0:00  
   Southern
   3:1-7    6 0:00
   10:25-31 6 1:00
   Mexican
   4:1-7    6 1:00
   10:25-31 6 0:00
   

5. Press F10 to Save the file and exit Memo.
6. If you previously had the World Time program running, close it.
7. Open the World Time program, find Indianapolis IN in the list of cities, and press ENTER. Indiana started observing Daylight Savings Time in 2006. For Indianapolis, change the Daylight Savings box so that Automatic and Northern are selected, and press F10 when done. Repeat this for any other cities in Indiana that you have defined.
8. Change all locations in Mexico so that Automatic and Mexican are selected.

Time Zone File Format

The next two lines define when to change time. For instance, under "Northern" above:

• 3 is for March (1=January - 12=December)
• 8-14 is the range of dates. The 2nd occurrence of a day in a month will be between the 8th and the 14th.
• 6 is for Sunday (0=Monday, 1=Tuesday - 6=Sunday)
• 1:00 means to set the clock 1:00 ahead of usual (i.e. spring forward)

Now that you know how to edit this, you can keep the HP 100LX and 200LX updated for any future changes in Daylight Time change dates.

Links:

• HP Palmtop Paper: World Time - New European Daylight Savings Time

The notes under 3. General Considerations on the introduction page. Various information are of interest.