Hi,

I'm surprised a 100 us is too fast for a computer in the 2+ GHz range.
This is a misunderstanding, its not the PC that monitors the index pulse but the motion board, in this case the USS. The USS will send to Mach at approximately 25ms intervals,
a count of how many clock pluses have occurred between two successive index signals.

Lets ay the USS has the same kernel frequency of the ESS, which is 4Mhz.
At 5000 rpm or 83.33 rotations per second and therefore the time between pulses is 0.012 seconds.

The USS will report a count of 4,000,000 x 0.012=48000.

There was indeed a thread on this very matter on the Warp9TD forum just a few weeks ago.....although it referred to the ESS rather than the USS, but the same principles
certainly apply, and most likely the same numbers also.

Craig