To the person with an answer: I'm still floundering as a rookie. I'm trying to get the timer0 and timer1 to count along with the program step on the 16c64 simulated on the mpsim. I tried clrf trisa, but bits 4 and 5 will not clear. Does anyone know how to get the timers running? Also, do the interrupts for timer1 work on the mpsim? Presently, I'm using the sim41603 version. If a newer version exists, I'll give it a try. Does anyone have the source code for the mpsim simulator? If so, how can I get a copy? Please help a rookie. Yours, Derrick Early