hi & thanks for your time,

i'm using mplab to step through a program for a 12c508a.(using step)
i get to the part of code to test for zero crossing.(code below)

chcycs    btfsc    gpio,3    ;check for 0
          goto     chcycs
lw        btfss    gpio,3    ;check for 1
          goto     lw

when i get to chcycs it just locks into chcycs.
even when i use step over it still does the same , gets locked !

how do i get past these 2 loops to keep checking the rest of the
program.
i've tried stimulus pins but didn't work !

i've been reading mike predkos book "programming  & customising the pic
microcontroller" & shows how to use dos sim.

i'm having trouble with the windows simulator.

any good information on how to use windows mplab.
a decent tutorial would be good.

thankyou for your time
glen