Thanks for the reply.

I made all variables words to give myself plenty of room, at least for now.
Ultimately, I want to get to pulses per minute, ie. RPMs with a range from maybe 240 RPM (4 cycles per sec) to maybe 4000 or 5000 (66 Hz to 85 Hz), give or take. I am flexible to a point. As far as resolution goes, something like 100 RPM increments (~2 Hz ?). Make any sense?