[LEAPSECS] POSIX Time

[Poul-Henning Kamp]

In message <20091010.102425.477146992.imp at bsdimp.com>, "M. Warner Losh" writes:


>Yes.  The original time_t (and long before it) definition was a bit

>vague.  It was written as "Seconds since Jan 1, 1970 GMT," but in

>practice it either had so large an error that the exact definition was

>irrelevant, or it was implemented as POSIX time_t is today.


Back then, the PDP's had a register that counted cycles on the mains
which was used for timekeeping.

At least anectotal evidence indicates that in several geographices
the first handful of leap-seconds were "smoothed out" in the mains,
because synchronous motor clocks were in widespread use by the
power-plants.

In the nordic net-group, all leapseconds in the 1980'ies were done
this way in the grid.  Af that deregulation, and because of
quartz-clocks, nobody thought it was necessary to make the number
of cycles look right when measured over a year any longer.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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