Mux Help

Posted by moarmango on
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Mux-Help-tp4025778.html

I have gotten up to Mux pretty smoothly, but the introduction of a 3rd input has left me frustrated.  I'm not sure how to even approach this puzzle.  I understand (I think) that the the canonical representation of Mux can be desribed:

X(not)YZ(not)+XYZ(not)+XY(not)Z+XYZ  - Is this starting off point correct? (4 Nots, 8 Ands, 3 Ors)

Up till now, all the Parts have been with 2 inputs that Nand and others have in its parameters.  Can Nand, Not, And, Or, and Xor have more than 2 inputs intrinsically?  In the Mux template there are 3 inputs, just having trouble on how to reconcile that with what up until now has been limited to 2 inputs.  During the Test, how is the third input incorporated if all the parts accept only 2 inputs?  Any guidance is sincerely appreciated.