PORTA, $1000:

    PORTA has three timer inputs(PA0 - PA2), four outputs(PA3 - PA6), and one bi-directional pin (PA7).



PORTB, $1004:

    PORTB is an output only port.  It consists of PB0 - PB7.


PORTC, $1003:

    PORTC is a bi-directional port.  DDRC (the data direction register for port C) is located at $1007.  Setting a LOW to one of DDRC's bits will cause the corresponding bit on PORTC to be an input, while setting a HIGH to one of DDRC's bits will cause the corresponding bit on PORTC to be an output.



PORTD, $1008:

    PORTD is another bi-directional port.  It's data direction register (DDRD) is located at $1009 and works in the same manner as DDRC.  PORTD also has the SPI system, and the SCI system (refer to the HC11 reference manual for instructions on using these).



PORTE, $100A:

    PORTE is an input only port.  This port can be used as a regular digital input port, or as an analog input.