Hardware/Interfacing
M68HC11 signals/pins available for interfacing:
- A 16-bit Address Bus A15-A0
- A15-A8 are available through PB7-PB0 in Expanded Mode
- A7-A0 through PC7-PC0 in Expanded Mode when AS=1
- An 8-bit Data Bus D7-D0
- D7-D0 through PC7-PC0 in Expanded Mode when E=1
- A 3-bit Control Bus E, AS, R/~W
- PD7 becomes R/~W in Expanded Mode
- PD6 becomes AS in Expanded Mode
- Pin E is always available (E=2 MHz; i.e., 500hs Event Clk)