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

Rich Alderson RichA at LivingComputerMuseum.org
Mon Jan 19 17:28:51 CST 2015

From: Peter Coghlan
Sent: Monday, January 19, 2015 4:24 AM

[failing to cite the previous posters, Mark Longridge and Johnny Bilquist]


>>> After trying to get Unix v5 to understand dates beyond the year 2000 I
>>> had to wonder if any of the older operating systems from the 1970s or
>>> older could do this.

>>> So, did any operating system programmers from this time period have
>>> the foresight to use 4 digits for the year? I just checked APL/360 and
>>> it seems that it does not.


>> TOPS-20? VMS?

> It was very near the end of the 1970s but VMS made a really good effort to
> handle times and dates well from the beginning.

Borrowing from TOPS-20 in the process, in spite of the VMS NIH mandate^Whabit.

> The areas where I think it could have been done better still are to have
> stored the time internally in UTC rather than local time while
> displaying local time and to have chosen an earlier base date than 17
> November 1858.

The use of the modified Julian date (2,400,000.5 dates less than the
Julian date) dates to 1957, when the Smithsonian Astronomical Observatory
adopted it to track Sputnik in 18 bits on a 36-bit IBM computer.  (Julian
dates, being used by astronomers, begin and end at noon rather than midnight.)


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:RichA at LivingComputerMuseum.org


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