Quote Originally Posted by flotulopex View Post
The four higher bits of PORTA are Inputs and when I checked out the levels on my PIC with my logic probe (set to TTL), using ~DCD would make the ports change status.
When using digital inputs, you need to make sure the external connection are either high or low. It sounds like what you are testing are floating (unconnected) inputs, which is a big no-no (not the testing of, but leaving inputs unconnected). Tie your inputs either high or low and repeat - you will see that they are not affected by your DCD command.