UPD784938 Datasheet, PDF (65/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 2 PIN FUNCTIONS
2.4 Cautions
When connecting unused pins, if the input/output mode is undefined for an input/output alternate function, it should
be connected to VDD with a resistor of several tens of kΩ (especially when the reset input pin becomes the low-level
input voltage or over upon powering on, and when input/output is switched by software.)
Preliminary User’s Manual U13987EJ1V0UM00
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