74138 1-of-8 inverting decoder/demultiplexer. +---+--+---+ +---+----+----+---+---+---*---+---+---+---+ S0 |1 +--+ 16| VCC |EN1|/EN2|/EN3| S2| S1| S0|/Y0|/Y1|...|/Y7| S1 |2 15| /Y0 +===+====+====+===+===+===*===+===+===+===+ S2 |3 14| /Y1 | 0 | X | X | X | X | X | 1 | 1 | 1 | 1 | /EN3 |4 74 13| /Y2 | 1 | 1 | X | X | X | X | 1 | 1 | 1 | 1 | /EN2 |5 138 12| /Y3 | 1 | 0 | 1 | X | X | X | 1 | 1 | 1 | 1 | EN1 |6 11| /Y4 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | /Y7 |7 10| /Y5 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | GND |8 9| /Y6 | 1 | 0 | 0 | . | . | . | 1 | 1 | . | 1 | +----------+ | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | +---+----+----+---+---+---*---+---+---+---+