I think that I know why I was wrong with my code.
I was trying to get output values from an only input port!. Funny, isn´t it?
It´s a beginner mistake.
In the 80C552, P5.X is only an input port.
I´ll try with P4.

Josh: I´d preffer to eject the people that are inside the car better than eject the wheels... :-)


Victor.