al him:
You should consider an altogether different design strategy for this program. It would be much easier to manage the four inputs separate from each other if you were to utilize a time slicing state machine. Please look at this previous posting and you can study a code tutorial that implements a state machine for a simple function similar to yours. Here is the link to the posting...

http://www.8052.com/forum/read.phtml?id=47505

Michael Karas