Tech: strange time changes on my computer

Subject: Tech: strange time changes on my computer
From: open mike
Date: 06 Apr 11 - 10:30 PM

today my computer "sprang ahead" one hour..as if it was just now day light savings time...the time changed earlier this year...March 13..but perhaps my 'puter thought it was supposed to do an april time change...could this be due to using XP, an older Operation system?

Subject: RE: Tech: strange time changes on my computer
From: EBarnacle
Date: 06 Apr 11 - 11:53 PM

Did it move up at the appropriate date, also?

Subject: RE: Tech: strange time changes on my computer
From: open mike
Date: 07 Apr 11 - 01:31 AM

as far as i know it did...
i have set it back an hour
and will see if it remembers
the "real" time. (i have had
problems with my cell phone
not getting the correct time)
when i thought that phones and
'puters were all supposed to
have the correct time without
needing to be set by humans...?

Subject: RE: Tech: strange time changes on my computer
From: Newport Boy
Date: 07 Apr 11 - 06:36 AM

I'm still using XP occasionally, and a month ago one of the updates was for a new listing of time zone settings. I think Microsoft does this most years, and I know my linux distribution does.

When you go to time and date settings, there should ba a box to tick (or not) for Daylight Saving (or Summer Time in English). Check if that's correct.

Phil

Subject: RE: Tech: strange time changes on my computer
From: JohnInKansas
Date: 07 Apr 11 - 11:51 AM

WinXP users encountered some difficulties with clock settings around the time of the Y2K hysteria, and also at the next "savings time" shifts following closely after. The DST/ST shifts around then produced some "fragmentation" of the time zones, and updates to tell the computers when to change were "erratic." Patches were issued to correct for all the mismatches; but some of the patches weren't compatible with others of them so there was some confusion.

I have't seen any comments about unusual changes recently.

Your computer sort of has to know what time it is in order to communicate on the web, but the the server you communicate with calculates an "offset" to correct the time your computer thinks it is so that the messages are properly tagged with the time the server is using. The correction is limited by the number of bits in the tag, so your error can't exceed something like 187 years.

Since a little before XP appeared, application of a large correction when you talk to a server should cause your computer to make an internal correction, but for large disagreements it's usual to correct about half the difference each time you hook up, so some mismatch can persist for a while although it should eventually "wipe itself out."

In past decades, it was necessary to have a battery in your computer to keep the clock running when the computer was down/off. If the battery died, the computer likely wouldn't even turn on. Batteries back then usually were fairly easily replaced; but in most computers now they're soldered (or welded) to the motherboard.

If your computer dates back to before XP and you upgraded from an older OS, you might have one of the old (usually NiCad or mercury rechargeable) batteries that could be replaced. (If your hardware is that old the clock battery likely has died; but you'd probably have already replaced it a couple of times and would remember how.)

Newer batteries are less likely to cause a dead computer, since the ones used now don't often "short circuit at failure." The charging voltage is sufficient to turn the clock back on at boot up, even if what's left of the battery acts more like a small capacitor than like a battery should. The likely result in newer computers is that the clock will lose track of the time if the computer's off for a while.

To "jump ahead" your clock would have to stop for 11 (or 23) hours, so that's not too likely to cause what you saw.

A more likely cause for a fairly recent (even an XP) computer would be an accidentaly mis-assignment of your time zone. There might be a zone, or a sub-zone of one, where the DST shift was at a different date than what you expected. When you get into the "local variations" it can be a puzzle to know what Microsoft thinks your zone should be called and the name they us in settings may look/sound like another one with slightly different switchover dates.

Telephones (cell/wireless ones) need the same sort of time synchronization as computers to be able to work; but the time doesn't really have to be all that accurate since they use similar "correction fctors" for for both kinds of communications. Reports some time back noted that it's common for two telephone systems to disagree by quite a bit, and you shouldn't expect your phone to know what time it is to better than about ± ten minutes or so - and sometimes a lot more than that.

If you click on the clock on your startup bar, it should show a "clicky" to change time, and clicking there should get a place to check time zone and to "synchronize" with a server. The "synchronize" menu may, for XP, still suggest a "Bureau of Standards clock" but Microsoft now synchs with their own "mirror clocks" (secondary standards) on their servers, and most of the primary standard (US) NBS clocks limit "public time checks." The Microsoft servers are generally within milliseconds (or probably better), even if sometimes their PR sounds like they don't know what century it is.

After you check everything out, we'll likely end up blaming it all on the little green men, misapplied fairy dust, or ghosts that came in while you were asleep. Or you can use my special other's excuse for everything and say "the cat did it."

John

Subject: RE: Tech: strange time changes on my computer
From: Jack Campin
Date: 08 Apr 11 - 05:52 AM

Blame the tsunami? From the RISKS Digest:

One of the two radio stations that emit Japan Standard Time signal stopped operating: the station is within 20 kilometers area (evacuation area) from the Fukushima Daiichi nuclear power plant.

Ever since the evacuation was announced, and the staff (2-4 people) left, the station stopped transmitting the signal. I suppose that the operator didn't want to possibly incorrect timing signal in the absence.

There are watches (including wrist watches) that can sync with the signal. CASIO, Seiko, Citizen and other makers of such clocks receive more than a dozen inquiries a day now. (I noticed something strange was going on with my watch that syncs at midnight, but that happens when the radio signal is not reachable due to indoor condition and didn't think much about it.)

The other station in the western part of Japan is in operation, but most heavily populated area, namely Tokyo and its surrounding area, is not covered well by the signal from that station.

Seismographs installed in mountain range and such uses the clock to sync the internal clock. The agency responsible for such instruments have resorted to use the wire signal for supplying the time information. Hmm, another risk of not so well tested software module and the somewhat unknown delay caused by wire transmission?