Jesper brings up a point often helpful in multiprocessor environments in syatems where most of the communication is master to slave.
Instead of the master constantly polling, a shared line between all slaves to tell the master to start polling can greatly reduce the time the master uses polling. I used this method in a system with 48 slaves where the only communication from slaves was "error".
Jesper: herovre er Mandag en helligdag "memorial day".

Have a memorable weekend

Erik