If you are using Microchip's PIC range,then know this simple thing ,the oscillator's frequency i.e.. system clock is divided by 4 inside the PIC to get one instruction cycle.It means that 4 clock is 1 instruction cycle.For example if you use 4Mhz oscillator as your clock source then your instruction cycle will be 4Mhz/4 = 1Mhz,so each instruction will take about 1000000Mhz/1000000us = 1us i.e.. 1 micro second.Eric007 said:BUT I also need to read the instruction cycles!!???