I'm trying to solve a little mystery. The pin PTB4 is also the /NMI pin. On reset, the internal pull-up is disabled in the PORT_PUE0 register. On the FRDM-KE06 board, there does not appear to be a pull up resistor in the schematic, and I can't find one on the board. There appears to be some pull-up somewhere, because I can measure 3 volts on the pin on the Freedom board. So, is there some pull up that's on by default, or is there a resistor on the schematic that I'm not seeing? In short, can the pin be left disconnected as it appears to be on the Freedom board, or does it need to have a pull-up resistor supplied?