Is it OK to connect Vcc directly to an A/D input? While testing some A/D functionality of my code recently, I'd brush a wire from Vcc and touch one of port 5's header pins, and see if I'd get 3FF.

Just wondering if I should have a resistor between the input and the supply. A resistor would give me a voltage drop proportional to whatever (slight) amount of current flows into an input. That's why I'd rather not have one if not needed. Hopefully the inputs are of sufficiently high impedance that current drain is negligible.

I know, I know. I'm about to go to Philip's Semiconductor site to read the electrical characteristics section of the 80c552 data sheet.