🚀 go-pugleaf

OS/8 (on DEC PDP-8's) had generously allocated an entire 3 (THREE,
count 'em, 3)bits for the year field in filesystem dates.  (In minor
defense, they only had 12-bit words, and needed 9 bits to hold
day-of-year.  Still, sounds like they didn't expect the OS to be
popular or long-lived.)

Originally, the 'base' year was 1960.  Late in 1967, someone finally
realized that something would have to be done about this.  The approach
they took was to use a sliding base year.  So, in encoding an ASCII
date into a filesystem date, the algorithm was (YEAR-1960) mod 8.  In
turning a filesystem date back to an ASCII date, it would pick the most
recent past year which would have given the encoding.  So, in 1968,
everything that had been lying around unchanged since 1960 suddenly
looked brand new.

If I recall correctly, they did NOT take the current day-of-year into
account when converting the year code back to readable form, so that
you could also find files which appeared to have been (have will been?)
created in the future -- that is, at a later date in the current year.

-- 
Paul Smee, Univ of Bristol Comp Centre, Bristol BS8 1TW, Tel +44 272 303132
 Sm...@bristol.ac.uk  :-)  (..!uunet!ukc!gdr.bath.ac.uk!exspes if you MUST)