All,

Thanks for all the responses, I probably should have mentioned that the sensors can be set off at the same time.

Also this is a very small robot, the biggest part of it is the PP3-type 9v battery, the PLCC AT89C52 is 'free-formed' to save space, so adding more components is going to be difficult.

I think scanning the I/O pins is going to be the best plan after all...

Thanks everyone for your input.


Chris Brooks