Hi there.

Erik is right. You should definitely visit that site and see those documents, even if you get your answers from here.

What I could make out is that you did the following:

1. configured port 0 for input by writing 0xFF.

2. Read Port0 into accumulator

3. Incremented the accumulator once.

Here is the answer of what I understood of your question.

Once you have read the port (be that any port) into accumulator, incrementing the accumulator WILL NOT change the state of the ports. They will still be configured for input. i.e. if you had used P0, it would still be high-Z. If you had used any of P1 - P3, it would still be outputting 0xFF (configured for input).

Regards
Aman