+---+--+---+ +---+---+---+---*---+ 4A1 |1 +--+ 16| VCC | A0| A1| S1| S0| Y | Y=S0.A0+S1.A1 3A0 |2 15| 4A0 +===+===+===+===*===+ 3A1 |3 14| S1 | X | X | 0 | 0 | 0 | 2A0 |4 13| Y4 | X | 0 | 0 | 1 | 0 | 2A1 |5 4019 12| Y3 | 0 | X | 1 | 0 | 0 | 1A0 |6 11| Y2 | X | 1 | X | 1 | 1 | 1A1 |7 10| Y1 | 1 | X | 1 | X | 1 | GND |8 9| S0 +---+---+---+---*---+ +----------+