b7 b6 b5 b4 b3 b2 b1 b0
 0  0  0  0  0  0  0  0 = 0
 0  0  0  0  0  0  0  1 = 1 = 1 * 2^0
 0  0  0  0  0  0  1  0 = 2 = 1 * 2^1 + 0 * 2^0
 0  0  0  0  0  0  1  1 = 3 = 1 * 2^1 + 1 * 2^0