Operating systems of the 1970s handling dates beyond the year 2000

Fred Cisin cisin at xenosoft.com
Mon Jan 19 10:18:42 CST 2015

On Mon, 19 Jan 2015, Robert Jarratt wrote:
> When I tried an early date with Ultrix to make the day of the week correct
> it said the date wasn't possible because it was before Ultrix was released.
> I found a suitable date in 1998.

Well, there are only 14 different calendars for the years - 7 different
ones for each starting day, and another 7 for leap years. Between 1901 and
2099, there is always a repeat every 28 years.   But there are numerous
more.  For THIS year (2105), you can get away with 1981, 1987, 1998, 2009,
. . .
(Note that 1900 and 2100 are not leap years because they are divisible by
100, but 2000 WAS a leap year, due to being divisible by 400.)

But, be careful when you reuse old wall calendars!
One of the first steps in a simple field sanity check is to ask the person
whether they know what the date is.  One glance at my wall, with a 1981
calendar and computers and computer books and magazines that happen to
be from that time period, and they know that I don't.

Grumpy Ol' Fred     		cisin at xenosoft.com

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