Devices connected to openPIC-compatible controllers should encode
sense and polarity as follows:
- 0 = high to low edge sensitive type enabled
+ 0 = low to high edge sensitive type enabled
1 = active low level sensitive type enabled
- 2 = low to high edge sensitive type enabled
- 3 = active high level sensitive type enabled
+ 2 = active high level sensitive type enabled
+ 3 = high to low edge sensitive type enabled
ISA PIC interrupt controllers should adhere to the ISA PIC
encodings listed below: