Hi all, It's my understanding that if interrupt-on-change is enabled, it is enabled for all four pins(RB4,5,6,7), no choosing. Let's use a PIC16C72 as an example. I'm not clear on the use of those four pins if some are used solely as output pins. My questions are: If I use two of the pins(RB4,5) for outputs, the other two(RB6,7) for inputs, and enable interrupt-on-change, will my manipulation of the two output pins cause an interrupt, or otherwise mangle the correct operation of the interrupt? Second question: will reading port B mess with the use of the interrupt-on-change feature? Do I need to use the first four pins(RB0,1,2,3) of port B output-only if I enable interrupt-on-change? Must I read port B only when servicing the interrupt? Thanks, Bob