View tc74hc151p datasheet:

TC74HC151P IL00 C-MOS 8-LINE-TO-1-LINE DATA SELECTOR/MULTIPLEXER —TOP VIEW— 4 X0 X3 IN 1 VDD 16 3 X1 2 X2 X2 IN 2 15 X4 IN 1 X3 X4 15 XC 5 X1 IN 3 14 X5 IN 14 X5 6 XC 13 X6 X0 IN 4 13 X6 IN 12 X7 XC OUT 5 12 X7 IN A B C INH OUT 6 XC 11 A IN 11 10 9 7 INH IN 10 B IN 7 CONTROL INPUTS ON 8 GND 9 C IN CHANNEL INH C B A 0 0 0 0 0 0 0 0 1 1 0 0 1 0 2 0 0 1 1 3 0 1 0 0 4 0 1 0 1 5 0 1 1 0 6 0 : LOW LEVEL 0 1 1 1 7 1 : HIGH LEVEL 1 x x x GND x : DON’T CARE