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Posted by sla29970 on 06/26/07 06:06
On Jun 25, 6:59 pm, ibupro...@painkiller.example.tld (Moe Trin) wrote:
> The main
> point is that there are some situations where _changing_ the clock
> setting is a Class 1 felony. To keep the system in time, you are
> allowed to _drift_ the clock, but as in the world, time never goes
> backwards, nor stand still.
Say somehow the clock is more than three seconds fast, so the system
is out of the range which is tolerated according to SEC guidelines for
trading. But the clock also runs a real-time process control system
where changing the frequency by 1 PPM will throw off synchronization.
What to do?
200 years ago navigators understood that the ship's chronometer would
not stay in agreement with the earth, but resetting the chronometer
made it unstable, so they kept logs of the difference between
chronometer and clock. 50 years ago there was still no such thing as
a clock which did not need to be reset, and the concept was
unthinkable. At some level of precision (which depends on how much
money was spent on the clock and engineering the systems around it)
that remains true.
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