Intro problem:
	Can we convert a logic expression to a circuit?
	Either A and B, or C and D, but not both
	(A ^ B) xor (C ^ D)
	Should be a piece of cake!
	Now:  All the way to transistors
		We'll do the xor in terms of other gates
	Can we simplify this?
		I won't do it ahead of time - we'll brainstorm together
		Might not find anything...but maybe we will!

Last time we made a little demultiplexer
	This time:  Use a bunch of board, and do a 3-bit multiplexer

Application time:  
	A control dial has 16 positions
	We want to transmit its location over a CAT-5 cable
	It can turn on 16 different lights in a different place
	Piece of cake now, right?

Another "building block" circuit:
	The adder
	Logic table for an adder
	With carry
	Let's set up a half adder, then a full adder, then something like a 3 bit adder
	A problem:  Propegation delay, and length
	How about we run two adders, one each way, and hook up the right one at the end?
		Width vs. depth, path length, transistor count, etc

At this point, at least a couple of you will wish you could play with this stuff
	I'm not prepared...
	A few ways:
		Arduino
		Raspberry Pi
		Historical port (serial or parallel)
		USB interface board
	I'll bring a robot at some point