View tc74hc155p datasheet:

TC74HC155P IL00D TTL DUAL 2-TO-4-LINE DECODER / 3-TO-8-LINE DECODER —TOP VIEW— DUAL 2-TO-4-LINE DECODER 14 INPUTS OUTPUTS EN 9 1C IN 1 VDD 16 15 EN Y0 C 10 EN C B A Y3 Y2 Y1 Y0 Y1 11 0 0 0 0 1 1 1 0 1EN IN 2 15 2C IN B Y2 12 0 0 0 1 1 1 0 1 A Y3 0 0 1 0 1 0 1 1 B IN 3 14 2EN IN 0 0 1 1 0 1 1 1 13 X 1 X X 1 1 1 1 1Y3 OUT 4 13 A IN 3 1 X X X 1 1 1 1 1Y2 OUT 5 12 2Y3 OUT EN C B A Y3 Y2 Y1 Y0 7 B Y0 0 1 0 0 1 1 1 0 6 1Y1 OUT 6 11 2Y2 OUT A Y1 0 1 0 1 1 1 0 1 5 Y2 1 0 1 1 0 1 0 1 1 C 4 1Y0 OUT 7 10 2Y1 OUT 2 EN Y3 EN 0 1 1 1 0 1 1 1 X 0 X X 1 1 1 1 GND 8 9 2Y0 OUT 1 X X X 1 1 1 1 3-TO-8-LINE DECODER 9 INPUTS OUTPUTS 13 A Y0 10 EN C B A Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0 3 B Y1 11 0 0 0 0 1 1 1 1 1 1 1 0