[ntp:questions] Assistance with PPS on Windows

David J Taylor david-taylor at blueyonder.co.uk.invalid
Fri May 6 04:22:27 UTC 2011

"unruh" <unruh at wormhole.physics.ubc.ca> wrote in message 
news:slrnis6idl.eqd.unruh at wormhole.physics.ubc.ca...
>> IIRC some BSD variants were claiming to get ~<150ns?
> I do not believe that you can service an interrupt, and read a system 
> clock
> that quickly. If you have specialised hardware on the PC (as someone
> suggested, a card with a counter on it which is switched on when the
> signal comes in) perhaps.

On the nearly five-year old Windows XP system here, getting the 32-bit 
tick count takes 4.2 ns, and getting the full time takes about 13 ns - 
this from user-mode.  So given the advances in processors and the 
different design of BSD 150ns doesn't sound impossible to me.  Pretty 
darned good, though!


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