[Al Skierkiewicz]

Sparks,
The RC guide speaks about the interface activity for the Digital I/O ports. See page 9 for a complete description. In effect what takes place is the inputs are all pulled up internally so that external devices only need to supply closing contacts to ground for a low or an open (pulled up internally) for a high. As outputs, the description indicates a standard tristate device in which the pin can be either high, low, or open circuit. The RC guide also points to the Programming Reference Guide for software control of the pins.