Finite state machines: implementing
	Step 4: Implement a circuit to generate the control signals
		One way to do this: use a ROM (read-only memory)
		Input to ROM: k-bit address
		Output from ROM: contents of location at given address
		Number of bits needed for address: inputs to truth table
			2 bits for state + 1 bit for input in this case
		Number of bits at each location: number of output bits + number of flip-flops
			4 bits in this case
	q1	q0	x	q1+	q0+	z1	z0	D1	T0
	0	0	0	1	0	0	1	1	0
	0	0	1	0	1	0	1	0	1
	0	1	0	0	1	1	1	0	0
	0	1	1	1	0	1	1	1	1
	1	0	0	0	1	1	1	0	1
	1	0	1	0	0	1	1	0	0
	1	1	0	d	d	d	d	d	d
	1	1	1	d	d	d	d	d	d