83Plus:Ports:39

This port only exists as a distinct port on the TI-83 Plus Silver Edition, the TI-84 Plus, and the TI-84 Plus Silver Edition. On the standard TI-83 Plus, it acts as a shadow of port 02.

Synopsis

Port Number: 39h

Function: GPIO Configuration

This port controls whether each of the GPIO pins serve for input or output. To designate a pin for output, reset its corresponding bit to 0; to set a pin for output, set the bit to 1.

See Port 3Ah for what each pin connects to.