The reason why the "1970-01-01 00:00:00GMT" epoch stuck was they
made the counter 32 bits to "fix the problem once and for all"
(Source: Dennis Ritchie, at breakfast at USENIX ATC 1998 New Orleans)
I've heard roughly the same story from another Murray Hill-ite. What
I find surprising about it is that most of the people involved in
Unics, later Unix, had worked on Multics. Multics, at least by the
1980s when I was using it, represented time as a FIXED BIN(71) (ie a
double-word quantity), counting in microseconds from 00:00 1-1-1900.
It was explicitly signed, so it could handle dates tens of millions of
years in each direction. It needed microsecond resolution, if not
accuracy, because the clock was locked so that no two processes could
obtains the same timestamp and therefore it could be used directly to
produce unique strings. For this reason the clock also had to be
monotonic, which made for entertainment every autumn, as although the
OS supported timezones being different for processes, it didn't
support summer time correctly.
ian
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