BS: strange time changes on my computer

Subject: RE: BS: strange time changes on my computer
From: Dave MacKenzie
Date: 14 Oct 10 - 06:48 PM

When I was an "occasional professional driver", I used to keep my wristwatch on Universal Standard Time (UST/GMT) all year because digital tachographs had to be entered in it to keep us in line with the rest of Europe.

Subject: RE: BS: strange time changes on my computer
From: Anne Lister
Date: 14 Oct 10 - 06:42 PM

If it's any consolation, my husband's computer (running Windows 7 and Snow Leopard) is also doing strange time anomalies.   He hasn't yet worked out why.

Subject: RE: BS: strange time changes on my computer
From: open mike
Date: 14 Oct 10 - 05:50 PM

i have windows xp

Subject: RE: BS: strange time changes on my computer
From: John MacKenzie
Date: 14 Oct 10 - 05:31 PM

We DO have a clock change here too. At the moment we are on BST [British Summer Time] which is one hour ahead of GMT. Clocks go back at the end of this month.

Subject: RE: BS: strange time changes on my computer
From: Tiger
Date: 14 Oct 10 - 05:21 PM

If you're running Windows 95 or 98, they probably don't know about the revised onset of DST.

Microsoft doesn't support those OSs any more, so you need to do it manually.

Subject: RE: BS: strange time changes on my computer
From: Ebbie
Date: 14 Oct 10 - 02:13 PM

"The most likely "explanation" for what you described is that when you thought your computer was an hour slow, and set it ahead an hour, the computer actually was right and the clock to which you referred to decide what time to set to was wrong."

Keep in mind that in the US, the Daylight Saving Time onset is earlier than it had been as has its departure. Our computers don't necessarily know that yet.

Subject: RE: BS: strange time changes on my computer
From: JohnInKansas
Date: 14 Oct 10 - 02:38 AM

It's remotely possible that your jump in time was due to a standard/daylight savings time change, since the change doesn't happen at the same time everywhere. If you have set your computer to believe that you're located someplace where there is a change in "local time offset" that differs from more widely accepted norms, the local time indicated on your computer will change according to the rules for whatever exotic place you've chosen. Although it shouldn't happen, and appears to be quite rare, local computer clock resets have been reported from opening ill-constructed web sites in backwater countries or from FTP exchanges with misconfigured sources.

The places that deviate in unusual ways from accepted dates for the generally accepted time changes are pretty rare; but there are a few. A change in time zone setting, or in rare cases selection of a different language (or language keyboard) may change your computer's conversion from the Universal Time used by the computer to local time displayed on your clock (and used to display the "time stamp" on files).

The most likely "explanation" for what you described is that when you thought your computer was an hour slow, and set it ahead an hour, the computer actually was right and the clock to which you referred to decide what time to set to was wrong. When you later found your computer an hour fast, it was then because you checked the time from a different clock that wasn't wrong so it looked like the computer had changed its own setting.

Of course that would be a pretty silly sort of thing to do, so we're pretty sure that's not the right explanation in your case.

It also must be mentioned that you've told us NOTHING about what OS you're using, so it's pretty difficult to discuss settings in much detail. You needn't feel bad about this omission, since it's normal practice for those who ask "technical questions" to omit anything that might contribute to getting valid advice. You're in good company.

Excepting the possibility that you might be late for your appointment to pick up your million dollar winnings at the lottery office, there's no real reason to be concerned about small inaccuracies in the time your computer thinks is correct.

The only place where it's really important that an accurate time be used is for Internet data exchanges. In this case, your computer tells a server what time your computer thinks it is, and the server calculates an "offset time" needed to correct your computer's time to the time the server thinks is correct. The same "offset" correction is used for the duration of that data exchange; but a new one is calculated when your computer talks to a different server.

Since the size of the "offset" is limited to "a few" binary digits, it is necessary that the time your computer believes is correct must be within a narrow range of the time that the server thinks is correct. The maximum allowed error (the maximum value of the offset) is something like 2¹⁶ bits, or about +/-185 years or so, if you need some sense of how accurate the clock setting on your computer really needs to be.

Recent Windows operating systems usually are scheduled to obtain a "time check" at regular intervals from a specific server, and will make corrections to the time set on your computer; but there normally is a limit on the "amount of change" at each correction. This means that a large error will be reduced but not necessarily eliminated at each check; but unless your computer's local clock rate is really off, repeated sync checks will eventually result in a close agreement between your computer's clock and the clock on the server from which it gets its sync checks.

There is, however, no specific standard for how accurate the server clock that's used to sync your computer's clock must be. The same method - time plus/minus offset - is used for cell phones and wireless communications, and "errors" on the servers of around ten minutes (especially with cell phone systems) appear to be quite common.

While the NBS and ONR clocks are kept very accurate, because of traffic overload it is quite common for them to reject attempts to ask them what time it is unless you've set up an account with an official "need" (i.e. with a government contract and password). You may get an answer if they're not too busy, but it's not something to count on. You can get a "radio check" at a dozen or so NBS/ONR synchronized frequencies, but of course that means you have to have an accurately calibrated finger to punch the time in on your computer - or a desk full of fairly sophisticated automatic comm equipment.

The only catastrophic problem with "time" is if your local clock is running at an incorrect rate. This generally means that your clock battery is failing, or that you've fried the crystal that keeps it running. A complete failure of either means that your computer will stop running - dead - defunct - inert - inactivated - and useless. But with fairly recent machines it's pretty rare.

John

Subject: BS: strange time changes on my computer
From: open mike
Date: 14 Oct 10 - 12:40 AM

Earlier today i looked and my computer was one hour behind. I re-set the clock for the correct time and just now i looked and it was one hour fast....any idea what would cause a computer to change times?
At first I thought it might be due to Daylight Savings Time or some automatic time change, but that doesn't happen for 3 1/2 weeks or so.

There used to be a phone number to call to get a recording about what time it was. So many people have computers and cell phones that tell them what time it is, that number has been dis-continued. We used to call POP-CORN (or POP then any 4 digits...some preferred pop-ACID)
so now: "who you gonna call?" Well, this site has the correct time
if you ever need to know...http://www.time.gov (in U.S. anyway)

This public service is cooperatively provided by the two time agencies of the United States: a Department of Commerce agency, the National Institute of Standards and Technology (NIST), and its military counterpart, the U. S. Naval Observatory (USNO). Readings from the clocks of these agencies contribute to world time, called Coordinated Universal Time (UTC)

Of course those mean people in Greenwich don't celebrate summer time
NOTE: Greenwich Mean Time (GMT) is the same all year around
There is no Summer Time / Daylight Savings Time

in the U.S. daylight savings time (what is the other time called?
Daylight Wasting Time?) changes in the spring and fall. ("spring ahead, fall behind") This year the clocks will be set back on Sun. Nov. 7. The days the clocks are changed are the Second Sunday in March and the First Sunday in November. (officially the time change occurs at 2 a.m. -- I wonder how many people actually change their clocks at that time? ) I also wonder how many people are late or early for school work or other things because they forget to change
their clocks.