An ontology of clocks

[Hal Murray]

There are two interesting corner cases that should get documented someplace.

Reading the RTC only gives you an answer to the second.  You can actually get 
a lot better than that if you spin and wait for it to tick.  (I carefully 
avoided using whatever word I should have used.)


Do you know about hanging bridges?
  http://www.leapsecond.com/pages/m12/sawtooth.htm

That problem shows up if you try to get a PPS pulse in via USB.  The USB 
clock is coarse enough to make things interesting.


-- 
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