Mark, thank you for clarifying. I thought it was something like that but my inexperience with internal voltage references left me confused. I have ordered some F1822 chips to experiment with.

So would you mind clarifying for me how I would go about using the single pin to take advantage of the internal reference diode. Do I understand correctly that this diode would replace the external diode we have been discussing, so all I would need is a pull-up resistor on the ADC pin? I still don't see how that would give me a reading that would very since I would still just be reading the voltage drop of the reference diode. Forgive me for being dense about this but I still don't get it.