Port A is a 3-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).
The Port A output buffers have symmetrical drive characteristics with both high sink and source
capability.
As inputs, Port A pins that are externally pulled low will source current if the pull-up
resistors are activated.
The Port A pins are tri-stated when a reset condition becomes active,even if the clock is not running.