Grumpy_Mike:
While it is normal to tie unused logic inputs to a level on logic ICs, I don't think it matters on the processor because the floating pickup on them is not going to make it's way into the rest of the logic unless the code invites them in.
I don't do anything with unused inputs and I have not experienced any problems.but don't I/O pins on microcontrollers tri-state
They default to inputs not tri-state.
Thanks for the correction 
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