[LEAPSECS] How good could civil timekeeping be?
Paul J. Ste. Marie
paul_j at ste-marie.org
Sun Feb 17 02:45:26 EST 2008
On 2/15/2008 9:11 PM, Rob Seaman allegedly wrote:
> 1a) Systems may need a table of leap seconds (after all, that's what
> all the kvetching has been about). Will this be required
> indefinitely? Maintenance procedures and such?
IBM mainframes have done this for at least 10-20 years. Their TOD
clocks are based on the original Unix definition, not the POSIX nonsense.
> 6) Airplanes navigate the skies. Software systems to do this surely
> both predate and postdate GPS. The internal models to realize this
> likely diverge in their interpretation of UTC.
The ATC system ran (runs? did the FAA ever get their act together?) on
IBM mainframes. See above. Navigation systems are more varying--the
one I've seen details of used three independent implementations on
disparate hardware platforms and a voting mechanism to resolve
differences.
--
--Paul
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