25 Jan
2011
25 Jan
'11
12:54 p.m.
On Tue, Jan 25, 2011 at 3:14 PM, Fred Cisin <cisin at xenosoft.com> wrote:
Any Unix type can tell you that history began at 00:00:00 January 1,
1970. ? But, they do allow negative timestamps...
Mac history began January 1, 1904... to avoid the leap year exception.
VMS counts 100ns quanta (each call to get the system time is
guaranteed to be unique) since November 17, 1858, coinciding with the
beginning of the Modified Julian Day epoch (handy for working with
some astronomical data sets). It's internally represented as a 64-bit
signed number - absolute times are positive, delta times (used with
batch jobs, as in "run four hours from now") are represented as
negative numbers, so timestamps can't be negative, but time values
_can_ (operator overloading, of a sort).
VMS time fails on 31-JUL-31086, but there are comments in the source
that the date formatting routines will fail on 1-Jan-10000 (the code
assumes that years are always represented in four digits).
So VMS is pretty robust at handling time, but has a known Y10K problem
(and less than 7989 years left to fix it!)
-ethan
The one thing that strikes me after reading this
thread is that it
seems there is no precise point when computing history began.
Huh? I thought it
began on January 13, 11 CE ?:-)