Hi Piclisters, I'm having a spot of bother with MPLAB in using the simulator function. I'm trying to simulate a small piece of code and want to simulate external pin inputs. I'm using the Pin Stimulus function provided, and have written the stimulus file as the user manual states, but it is still not working. example of stimulus file : cycle RA2 RA1 RA0 20 0 1 0 40 1 1 0 55 1 0 1 etc...etc...etc.... My sim setup is for 16F877 @ 20Mhz and I'm using MPLAB 4.10 Everything else is working fine with the simulation I just can't get the pin stimulus to work and I need to be able to use it. Do i have to set the TRISA reg to in's or outs..? Does anyone haveany ideas on how to fix this or get around the problem...??????? Thanks Adam