Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!microsoft!jamesth
From: jamesth@microsoft.UUCP (James THIELE)
Newsgroups: comp.sys.mac.misc
Subject: Re: What happened in 1904?
Message-ID: <55874@microsoft.UUCP>
Date: 17 Jul 90 15:40:18 GMT
References: <1990Jul13.131831.26890@ux1.cso.uiuc.edu> <5099@mace.cc.purdue.edu> <9151@goofy.Apple.COM>
Reply-To: jamesth@microsoft.UUCP (James THIELE)
Organization: Microsoft Corp., Redmond WA
Lines: 49

In article <9151@goofy.Apple.COM> rmh@apple.com (Rick Holzgrafe) writes:
>In article <5099@mace.cc.purdue.edu> omalley@mace.cc.purdue.edu (John 
>O'Malley) writes:
>> In article <1990Jul13.131831.26890@ux1.cso.uiuc.edu> rolf@sparc1 writes:
|| |
|| |  You probably have noticed that if your battery gets removed, or the
|| |PRAM gets zapped that you get some files with dates in 1904. I heard
|| |a LONG time ago that there was a joke of some sort behind this.
|| |   Anybody know it?
|| 
|| The year 1900, despite the fact that it is evenly divisible by 4, was
|| not a leap year.  1904 was a leap year.
|| 
|| I thought I heard that Apple didn't wanna bother programming in that
|| exception, so they had the clock start in 1904 instead of 1900.
|
|That's probably correct. Figure it this way: the Mac stores the 
|date-and-time as a count of seconds in an unsigned 32-bit integer. That 
|gives you a range of zero to (a little more than) 4 billion seconds. 
|That's a range of (a little more than) 135 years.
|
|OK, what years should we cover? How about all of this century, and 35 or 
|40 years of the next? That should mean that all our users, young and old, 
|can deal with nearly all the dates within their lifetimes. OK then, 1900 - 
|2035 or so.
|
|Then, as John suggested, the programmer speaks up and says "The 
|day-of-the-week calculations get real easy if the first year is a leap 
|year. 1900 wasn't. How about if we start in 1904?" Everyone agrees, and 
|the final range becomes 1904-2040.
|
|Well, I have no idea if it was really like that. But I thought this 
|through while writing a calendar-page app recently, and it makes sense. 
|And there's no joke here, unless you think the Julian calendar itself is a 
|bit of a giggle. (Ever checked out September, 1752? I'll bet the 
|programmer was glad he didn't have to cover *that* one! :-)
|

The problem is even stickier if you consider localization.  Not all
European countries changed to the Gregorian calendar in 1752 - the
Soviet Union (aka Russia) change until after the Bolshevik Revolution,
so 1900 *was* a leap year in Czarist Russia.

But Apple *really* punted on localization by not including Moslem, Jewish,
Japanese, Mayan and so on calendars as options.  Why shouldn't there be
a control panel option to choose which system to show dates in? :-)

James Thiele -- microsoft!jamesth
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