SHCC WYSIWYG Article from June 1999

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This article of the month was written by Don VanSyckel, the club president.  This article appeared in the June 1999 WYSIWYG newsletter.

Year 2000 Fix Come in Unexpected Forms

by Don VanSyckel

It recently came to my attention that there is another class of appliance you probably have in your home which may not be Year 2000 (Y2K) ready.  That's your VCR and possibly some other things which do scheduling.  Here's the problem: When you program your VCR you supply the date in the form of month and day, but not the year.  Since you don't supply the year what's the big deal?

Well, remember when you program your VCR with the date it displays the day of the week, Monday, Tuesday, etc.  The VCR uses the year to determine what day of the week any specified date is.  Let's take January 1 for example, in 1998 it was a Thursday, in 1999 it was a Friday, and in 2000 it will be a Saturday.  Granted, if your VCR is not Y2K ready, you could ignore the day of the week when you program it and everything should work just fine, almost.  Some VCRs also allow programming to record 'every Tuesday' and 'every weekday'.  Of course these functions won't work if the day of the week is incorrect.  Since many people find programming their VCR challenging, the wrong day of the week being displayed during programming is only going to add to the confusion.  Also in just using a VCR that is not Y2K ready, you'll have to remember to check the date every March 1st to verify that the VCR did or did not do a leap day in accordance with what the actual year is.

So what do you do? Throw away your VCR if it's not Y2K ready? Well you can (if you would, throw them my way), but I can't afford to pitch a couple of perfectly good units.  So is there an alternative which will cause the correct date, including the day of the week, to be displayed? Yes, it seems like it might be complicated, but actually it turns out to be rather straight forward.

Let's think about the calendar.  Not any particular year but in general, and let's consider January 1st.  January 1st can only be seven different values, Sunday through Saturday.  Therefore, there are only seven different calendars for non-leap years and seven different calendars for leap years or 14 all together.  In other words, any year that has ever been, and any year that ever will be, has to be one of 14 different calendars.

With this in mind, if your VCR is not Y2K ready you can simply set it to a year that has the same calendar as 2000 has.  Since 2000 is a leap year, obviously the 'substitute year' also must be a leap year.  As it turns out, the most recent year that matches 2000 is 1972.  If your VCR won't handle 2000, set it to 1972, and althrough it is 2000, everything will function normally.  Actually, the years 1972 through 1999 exactly match the years 2000 through 2027.  Then the sequence repeats again during 2028 through 2055, and again and again until the year 2100, when things change.  (2100 is not a leap year so the sequence will change, but still repeat on a 28 year cycle.  Look the follow up to this article in 2099, when I will discuss the fix for 2100 and beyond.)  So using this scheme, your VCR has a perpetual clock if you can remember to set it once every 28 years and on the century on January 1st.

For those of you who can't keep your VCR powered up for 28 years straight because of power failures, you move from one house to another, or unplug it to paint the room, you just need to subtract 28 from the year to get a year between 1972 and 1999 inclusive, or you can refer to the table below. Maybe clip the table out and tape it to the bottom of your VCR.

A note about leap years: Years divisible evenly by 4 are leap years, unless it is a century then it is not a leap year, unless it is divisible evenly by 400 then it is a leap year like normal.  This odd correction is because the solar year is slightly less that 365.25 days so we skip 3 leap years every 400 years.  This gives us 365.2425 days per year average.  This averaging accounts for why the first day of Spring, Summer, Fall, and Winter is usually the 21st of its respective month but does move to the 20th or 22nd occasionally.

NON-LEAP YEARS, January 1 is on:
Sun197819891995200620172023203420452051
Mon197319791990200120072018202920352046
Tue197419851991200220132019203020412047
Wed197519861997200320142025203120422053
Thu198119871998200920152026203720432054
Fri198219931999201020212027203820492055
Sat197719831994200520112022203320392050
LEAP YEARS, January 1 is on:
Sun198420122040
Mon199620242052
Tue198020082036
Wed199220202048
Thu197620042032
Fri198820162044
Sat197220002028

End of Article

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