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World TimeFine Tune Daylight Savings Time Switch Dates (100/200LX)
On the 100/200LX you can set a World Time city to Automatically change to Daylight Savings Time. World Time (as shipped) only recognizes three time zones: European (most of Europe), Northern (most of North America) and Southern (most of the southern hemisphere).
These work for most cities in the All Cities List, but the United Kingdom and several other countries don't have the same DST switch dates. If you want to customize the DST time changes for your area, HP did leave a way to add 23 additional Time Zones. What follows is not in the 100/200LX User's Guides, but was gleaned from several discussions on CompuServe's HPHAND forum. You should test it out in your situation before relying on it.
The file D:\_SYS\TIMEZONE .DAT (on the ROM disk) is a simple ASCII file that contains a list of DST transition dates. It looks like this:
3:25-31 6 1:00
9:24-30 6 0:00
4:1-7 6 1:00
10:25-31 6 0:00
3:1-7 6 0:00
10:25-31 6 1:00
You cannot modify this file, but you can copy it to C:\_DAT and edit it there. If World Time sees a copy of TIMEZONE.DAT in C:\_DAT, it will use that copy instead of the one in D:\_SYS.
Copy TIMEZONE.DAT to C:\_DAT and edit it with MEMO. For the United Kingdom (this is an example only, verify the actual dates), append the following three lines to the end of the file and save the file:
3:25-31 6 1:00
10:23-31 6 0:00
The second line above tells the 100/200LX when to "Spring forward," the third line when to "Fall back." For example, the second line above translates (roughly) as follows: "In the 3rd month (March), on the date between 25-31 that Sunday (day 6) falls, add 1:00 hour to the time." (The days Monday through Sunday are numbered 0 through 6. The months January through December are numbered 1 through 12.)
To update the United Kingdom cities, for example, highlight the desired city and press (ENTER) to display the City screen.
Tab down to Automatic in the Daylight Savings box and use the down arrow to select United Kingdom. Press (F10) to enter the change.
Do this with each city you want to change. You can create a system macro to automate the process.
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