A student writes:

	Hi Dr. Patt. In the last question in the problem set, 
	in which we are to implement the block labelled logic 
	as in section c.5.1, do we have to use 2 mux's as the 
	appendix decribes, or can we do with one mux?  Are we 
	free to use any logic we wish?

	Sincerely yours,
	<<name withheld to protect the student who thinks he has a better way>>

Do it however you wish.  I spelled it out the way I did in an attempt to make it clear.  If 
you have a better way, by all means.

Yale Patt