Some of you may have seen my earlier post concerning the apparent failure of
a PICC74A to work properly with it's A/D Vref set to reference the voltage
on AN3 instead of chip Vdd. It was behaving as if Vref was set to Vdd no
matter what software selection was made.  Well, I finally solved it, and the
answer is pretty embarrassing so I though I might save someone else's face
by exposing my gaffe.

For convenience (read laziness) in my breadboard circuit I only hooked up
pin 32 to Vdd and pin 12 to Vss leaving pins 31 and 11 floating because I
assumed they were redundant. Well, they're not. Leaving those 'redundant'
pins floating makes the AN3 ineffective as a Vref for some reason I do not
understand. It is odd that other than the A/D, the rest of the chip worked
fine with those pins left unconnected. I am going to speculate that Vdd was
making it's way through a forward biased input protection diode or something
thus allowing the digital portion to function, but wreaking havoc with the
analog section....whatever, at least now things behave correctly.

Moral - connect all your power pins please and thanks to everyone who
patiently tried to 'debug' my problem.

-Paul Howell