timer question

On a QNX4 system with a ticksize of 10ms,
how long will it take to miss a 40 ms
timer event by the ticksize?

Is it ticksize/(delta)ticksize=
10ms/(1ms - 0.999847ms) * ticksize = 10ms/153ns
10ms
=65s?

Is the 0.999847ms limitation on PC hardware
documented somewhere in QNX documentation?