+---+--+---+ +---+---+---*---+ 1A |1 +--+ 14| VCC | A | B | C | Y | Y = A+B+C 1B |2 13| 3A +===+===+===*===+ 2A |3 12| 3B | 0 | 0 | 0 | 0 | 2B |4 4075 11| 3C | 0 | 0 | 1 | 1 | 2C |5 10| 3Y | 0 | 1 | X | 1 | 2Y |6 9| 1Y | 1 | X | X | 1 | GND |7 8| 1C +---+---+---*---+ +----------+