I've been starting to design the electronic system which will control my CNC mill and already I have hit a potential problem. My problem it seems is the number of inputs and outputs available through a parrallel port. I'm designing a four axis machine so that will be 1 limit switch for each end of each axis = 8 limit switches !.

8 inputs just for limits seems a little excessive, even for a 3 axis, by my reaconing 6 would be required.

Is there an error in my thinking here or is this normal and accepted ?