Thank you Valentin for your help. I see what you are saying about having to only take 5 microseconds for the instructions and then complement the output.

By the way Mahmood, I didn't want the answer given to me, I just wanted to know whether or not I was on the right track. If you had read my original post it would be evident that I attempted this problem BEFORE posting it.

Thanks again Valentin, I appreciate your helpful comments.

Paul