Quote Originally Posted by mister_e View Post
Some will set unused I/o as output, assign a level and let them float. In conjunction with a nice ground plane this might work.
I make them outputs and tie them to ground through 10k. Inputs if somehow allowed to float make great antennas for noise / outputs on the other hand if somehow get switched on, increase your power consumption. Bottom line is tie them the way that works best for your application, but do not let them float.