> >I'm trying to drive an array of <= 16 LEDs from a PIC

Just thought, check the archives. Around a year ago there was a
prolonged discussion on (what started as) a 4x4 array using only
PIC pins. Don't recall how it ended up, but quite a few practical
suggestions re input/output/tri-state conditions to access any LED

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http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.