Hello

This is my first posting. Hope not to be much of a pain with this question. But I am using a 16F84 to make a tachometer. I am reading the pulse from a photo interrupt. I can get the MCU to read the pulsin signal I'm just not sure if I am processing the data correctly. Please bear in mind that I am a complete novice at this. Extra info I guess would be that I am taking a pulse off a small dc motor with a 1.5" disk as an encoder. I am using 2 holes on a 1.25" bolt center, each hole 1/8" diameter. If anyone can point me in the right direction, it would be greatly appreciated.