I have an ancient Sony SLV-757NC VCR that I’m still rather fond of. Trouble is, its built-in clock/calendar only covers the years from 1989 to 2004. Can I still keep using in future years?
The answer is yes! If you have a similarly ancient machine that you want to keep running, the trick is to find a year within the range that the machine understands, that has the same calendar as the current year. There are only 14 different calendars in the Gregorian system: 7 for non-leap years, and 7 for leap years.
So there are bound to be years within the range of the machine that have the correct calendar for any non-leap year. The only real problem is leap years, since the machine’s range is liable to include too few of these.
The workaround for this is to use two different alternative years in a leap year: one for the first part up to the 28th of February, and another for the part from the 1st of March onwards. For the 29th of February, you’ll have to fudge it; perhaps use the same year as the 28th, but pretend the 29th is “March 1st”.
The following table lists alternative years that have the same calendar as the desired years, or parts thereof:
| Desired Year | Alternative Year | |
|---|---|---|
| To Feb 28 | From Mar 1 | |
| 2005 | 1994 | |
| 2006 | 1989, 1995 | |
| 2007 | 1990, 2001 | |
| 2008 | 1991, 2002 | 1997, 2003 |
| 2009 | 1998 | |
| 2010 | 1993, 1999 | |
| 2011 | 1994 | |
| 2012 | 1989, 1995 | 1990, 2001 |
| 2013 | 1991, 2002 | |
| 2014 | 1997, 2003 | |
| 2015 | 1998 | |
| 2016 | 1993, 1999 | 1994 |
It turns out that it’s not until 2020 that I can reuse an actual leap year, namely 1992. In fact, in 2017, I can set the year to 1989, then simply let it run on from there (becoming 1990 in 2018 and so on), and the calendar will remain correct until 2032 (corresponding to 2004). Assuming my VCR stays working that long.
Created 2004 September 29 by Lawrence D’Oliveiro.