Daylight saving correction

[Roedy Green]

Your computer should have automatically set your PC clock ahead 1 hour
at 2AM this morning. If you want to check that it worked ok, and if
not correct the problem and resynch your clock with an atomic source,
see

http://mindprod.com/webstart/setclock.html

for general lore on DST see
http://mindprod.com/jgloss/dst.html

--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Roedy Green]

Your computer should have automatically set your PC clock ahead 1 hour
at 2AM this morning.

That applies to the USA and Canada only. Other parts of the world
will have other correction dates.
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Arne Vajhøj]

Your computer should have automatically set your PC clock ahead 1 hour
at 2AM this morning. If you want to check that it worked ok, and if
not correct the problem and resynch your clock with an atomic source,
see

C:\>javac DST.java
DST.java:1: class, interface, or enum expected
Your computer should have automatically set your PC clock ahead 1 hour
^
1 error

Arne

 

[Arne Vajhøj]

That applies to the USA and Canada only.

And only to OS's that has such a feature.

But it is still not on topic here.

Arne

 

[Dr J R Stockton]

In comp.lang.java.programmer message <i53qp5dnm4ro53afcfkqvbgqr7kl9g4dea
@4ax.com>, Sun, 14 Mar 2010 09:22:18, Roedy Green <see_website@mindprod.
com.invalid> posted:

Your computer should have automatically set your PC clock ahead 1 hour
at 2AM this morning.

Codswallop and balderdash. The proper date for that is the last Sunday
in March and the proper time is 01:00 UTC (or GMT), which all Canadians
should realise. The proper date to change back is the last Sunday in
October, at the same UTC.

Except, of course, for those in the Southern Hemisphere.

Both except those near the Equator, in Iceland, or on the ISS - etc.

 

[Joshua Cranmer]

Your computer should have automatically set your PC clock ahead 1 hour
at 2AM this morning. If you want to check that it worked ok, and if
not correct the problem and resynch your clock with an atomic source,
see

http://mindprod.com/webstart/setclock.html

Only if you are part of the ~5% of the world population who lives in
parts of North America and the Caribbean islands.

A more complete (but not fully correct) chart, taken courtesy of another
newsgroup that requires coordination between people from many different
countries (most notably U.S., Canada, a variety of European countries,
New Zealand, Japan, among others):

Sunday, February 21:
-1 hour: South, Southeast, and Central-West Brazil (GO, DF, MG, ES, RJ,
SP, PR, SC, RS, MS, MT)

Sunday, March 14:
+1 hour: Canada (except Saskatchewan (excluding western parts that are in
Mountain Time) and the areas around Resolute (NU),
Atikokan (ON) and Southampton Island (NU),
Blanc-Sablon (PQ), and Dawson Creek and Fort Saint
John (BC))
United States (except Hawaii and most (non-Navajo areas) of
Arizona)
parts of Mexico near US border (except Sonora)
Bahamas
Bermuda
Cuba
Turks & Caicos Islands
St. Pierre & Miquelon
Thule area (Greenland)

-1 hour: Uruguay
San Luis area (Argentina)
Palmer Station (Antarctica)

Monday, March 22:
+1 hour: Iran

Friday, March 26:
+1 hour: Jordan, Syria, Israel, Palestinian Territories

Sunday, March 28:
+1 hour: all of Europe (except Iceland and Georgia), including:
all of Russia (except Novokuznetsk area)
all of Turkey
Armenia
Azerbaijan
Cyprus
Faroe Islands
Tunisia
Lebanon
most of Greenland (except Thule and Danmarkshavn areas)

-1 hour: Samoa
Fiji

Thursday, April 1:
+1 hour: Bangladesh

Sunday, April 4:
-1 hour: much of Australia (Victoria, NSW, Tasmania, SA, ACT?)
New Zealand
Namibia
Chile
McMurdo and Amundsen-Scott Stations (Antarctica)

-0.5 hours: Lord Howe Island (Australia)

+1 hour: Mexico (except Sonora and parts near US border)

Sunday, April 11:
-1 hour: Paraguay

Thursday, April 15:
+1 hour: Pakistan

Sunday, April 18:
-1 hour: Falkland Islands

Friday, April 30:
+1 hour: Egypt

On second thought, don't bother posting DST correction announcements.
The newsgroup would be flooded throughout late March and April, as well
as a similar timeframe near the other equinox.

 

[Roedy Green]

No it shouldn't!

I presume by that you mean the UTC time should not have shifted, just
the displayed local time? Or that this only applies to Canada and the
USA?
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Roedy Green]

Codswallop and balderdash. The proper date for that is the last Sunday
in March and the proper time is 01:00 UTC (or GMT), which all Canadians
should realise. The proper date to change back is the last Sunday in
October, at the same UTC.

Not any more. Remember Mr. Bush extended the range of DST.

The 2:00 AM local time rule is what I learned as a young child, and in
general that is when public clocks change in my part of the world.

What is your source for 1:00 UTC?
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Roedy Green]

Codswallop and balderdash. The proper date for that is the last Sunday
in March and the proper time is 01:00 UTC (or GMT), which all Canadians
should realise. The proper date to change back is the last Sunday in
October, at the same UTC.

according to TimeZone.inDaylightTime, for PST, the shift happened
2010-03-14.
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Dr J R Stockton]

In comp.lang.java.programmer message <c5r0q516d182h35q6jsad1nk7hdl5iuv5t
@4ax.com>, Tue, 16 Mar 2010 22:49:26, Roedy Green <see_website@mindprod.
com.invalid> posted:

Not any more. Remember Mr. Bush extended the range of DST.

Mr Bush is, and was, irrelevant (and North America previously used the
first Sunday in April). Moreover, while the Energy Policy Act of 2005
applied throughout America, that part of the Act did not have effect
throughout America. The States are not in all respects United. Neither
is Canada; the Provinces decided independently to use the new days, but
do not all change at the same local time - NRC has a Time FAQ.

The 2:00 AM local time rule is what I learned as a young child, and in
general that is when public clocks change in my part of the world.

But you said nothing about your part of the world in your initial post.
You wrote "Your computer should have automatically set your PC clock
ahead 1 hour at 2AM this morning.". You were addressing a world-wide,
if sparse, readership. The whole world does not revolve around your
country's southern appendage. It generally agrees with what Churchill
might have said about them.

That sentence is full of error. There, "computer" should be plural; I
have four - the one which runs DOS cannot alter its time; the correct
time to change in Spring is 01:00 previous local (01:00 UTC or GMT); the
correct date is the last Sunday in March ... and it's unreasonable to
expect them to do anything at that sort of time, since they are all
turned completely off, externally to themselves[*].

What is your source for 1:00 UTC?

For such things, consult
<URL:http://www.merlyn.demon.co.uk/uksumtim.htm>.
The efficient source is The Summer Time Order 2002, of which there is a
copy at <http://www.opsi.gov.uk/si/si2002/20020262.htm>. That is an
Order of your Monarch, albeit not one aimed at you, implementing for the
UK an EU Directive. One hopes that the Lord of Mann issued a similar
order.


[*] On general grounds, virtually every night; with special care to do
so around local 00:59-02:01 on the last Sunday in March, and around
local 00:59-02:01 on the last Sunday in October.

 

[Roedy Green]

National TV gave me the impression DST was informally implemented
across Canada, with the exception of Saskatchewan who stick to "God's
time". I was astounded to find out it is far from so.


In most of Canada, DST begins and ends at 2 AM on the same days as the
USA. However, in Newfoundland and Labrador, DST begins one minute
after midnight local time on the second Sunday in March. On the first
Sunday in November time returns to standard at one minute after
midnight local time.

A few areas of Canada don’t use DST at all including Fort St. John,
Charlie Lake, Taylor and Dawson Creek, Creston in British Columbia,
and most of Saskatchewan (except Denare Beach and Creighton).

It seems so odd I could have visited Creston several times without
noticing this.
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Roedy Green]

and it's unreasonable to
expect them to do anything at that sort of time, since they are all
turned completely off, externally to themselves[*].

PCs running recent versions of Windows adjust themselves just fine
when you turn them back on. For the recent Windows, nothing happens to
the CMOS clock, just to the software that displays the current value.

If they are powered on, you can see them change (in my case) bang on
at 2 AM).

For XT-era, what happened depended on your proprietary clock driver.
For AT-era, you had to manually set the clock forward and back an hour
since the CMOS clock kept local time. An the OS was not prepared to do
the sort of timezone bookkeeping that Java and Windows 7 do. What we
do now was not really feasible without weekly Internet automatic
updates to keep time zone tables up to date.

DST is an idiotic idea that just complicates timekeeping and
guarantees errors. I wonder how many people have died as a result of
errors caused by DST. I wonder the aggregate cost of all the missed
appointments.


--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Dr J R Stockton]

In comp.lang.java.programmer message <39GdnSt5Lps88T7WnZ2dnUVZ7odi4p2d@b
rightview.co.uk>, Fri, 19 Mar 2010 12:22:57, bugbear <bugbear@trim_paper
mule.co.uk_trim> posted:

The latter...

Parts of the USA and parts of Canada do not use DST. Part of Canada
changes at different times. Other parts of North America, apparently
including Cuba, use the same date for at least one of the annual
changes.

Uruguay & Paraguay also change on 2 Sun Mar, but not as described.

 

[Dr J R Stockton]

In comp.lang.java.programmer message <d7j9q553fncdn1sbvue4m086rri4v6ou6i
@4ax.com>, Sat, 20 Mar 2010 06:35:06, Roedy Green <see_website@mindprod.
com.invalid> posted:

and it's unreasonable to
expect them to do anything at that sort of time, since they are all
turned completely off, externally to themselves[*].

PCs running recent versions of Windows adjust themselves just fine
when you turn them back on.

Of course. But that is different.

For the recent Windows, nothing happens to
the CMOS clock, just to the software that displays the current value.

I have a 16-bit DOS program, INT-TEST via sig line 3, which tests
various low-level things concerning date and time. In a week's time,
I'll be able to test it in Summer Time in WinXP sp3 on P4/3G.

It will be interesting to see what CMD.EXE and COMMAND.COM windows then
show as the apparent behaviour of the CMOS clock. Feel free to try it!
It should be enough to run it, then <cr>, then read the "Peep" line,
then Q to quit.

If the CMOS clock does not maintain local civil time, it ought to hold
UTC; it seems half-measures to hold local standard (Winter) time,

 

[Tim Slattery]

In most of Canada, DST begins and ends at 2 AM on the same days as the
USA. However, in Newfoundland and Labrador, DST begins one minute
after midnight local time on the second Sunday in March. On the first
Sunday in November time returns to standard at one minute after
midnight local time.

And remember that Newfoundland time is thirty minutes ahead of
Atlantic time (Nova Scotia, etc). They're in their own world!

 

[Dr J R Stockton]

In comp.lang.java.programmer message <[email protected]
on.merlyn.invalid>, Sun, 21 Mar 2010 15:38:00, Dr J R Stockton

In comp.lang.java.programmer message <d7j9q553fncdn1sbvue4m086rri4v6ou6i
@4ax.com>, Sat, 20 Mar 2010 06:35:06, Roedy Green <see_website@mindprod.
com.invalid> posted:

and it's unreasonable to
expect them to do anything at that sort of time, since they are all
turned completely off, externally to themselves[*].

PCs running recent versions of Windows adjust themselves just fine
when you turn them back on.

Of course. But that is different.

For the recent Windows, nothing happens to
the CMOS clock, just to the software that displays the current value.

I have a 16-bit DOS program, INT-TEST via sig line 3, which tests
various low-level things concerning date and time. In a week's time,
I'll be able to test it in Summer Time in WinXP sp3 on P4/3G.

It will be interesting to see what CMD.EXE and COMMAND.COM windows then
show as the apparent behaviour of the CMOS clock. Feel free to try it!
It should be enough to run it, then <cr>, then read the "Peep" line,
then Q to quit.

If the CMOS clock does not maintain local civil time, it ought to hold
UTC; it seems half-measures to hold local standard (Winter) time,

It is now Summer Time here.

Win XP sp3, both COMMAND.COM and CMD.EXE - the program says that both
the RTC and the software DOS clock show UK civil time. Therefore, the
apparent RTC has been put forward by an hour. I do not know what that
proves, though.