How to know what pin triggered an interrupt?

[sheepdog]

My guess is that your original code a couple of posts above would be faster... There's a lot of bit shuffling that goes on with REV and NCD.
Also, what happens if none of the pins are hit? If more than one pin is hit?

"reversed_a = a REV 8 'reverse 8 bits of variable a in which I mirrored PORTA register"
B0 = portx
B1 = ^ B0 ' Reverse state of bits of B0
B0 = NCD B1
select case etc

Bruces would probably be the fastest way, I have an affliction for making thinks more complex than perhaps need be. Did not realise pins default high etc.
All the best