G'day. Just wondering if anyone could let me know if they can see any bugs in this program... been over it heaps but I still cant see why its not doing what its suppose to be doing. What it is suppose to be doing is tuning on a led out of port Rb4 when an input is recived from port Ra0. thanks. The Fire Starter. Code: Code: maclib 'p16f8x.inc' ; device pic16f84,xt_osc,wdt_off,pwrt_on,protect_off ; leds = portb ;led output port Input = porta ; dir_b = 00h ;all out dir_a = 01h ;RA0 in ; org 0ch ;start of ram space ; org 0 ;reset vector ; jmp start ;go to beginning of program on reset ; org 5 ;start of code space ; ; ; sets up leds and direction registers ; start mov leds,#0 ;start with all leds off setb rp0 ;point to register page 1 mov trisb,#dir_b ;set port b data direction register mov trisa,#dir_a ;set port a data direction register clrb rp0 ;point back to register page 0 ; ; ; main loop to light leds when input on pin Ra0 ; ; ledon mov leds,8 ;turn leds on at port Rb4 jmp mainloop ;do it forever ; ; mainloop cje 1,input,ledon ;compare the input to the value 1 and jump if equal mov leds,0 ;turn leds off if input is not present jmp mainloop ;do it forever