View tc74hc253p datasheet:

TC74HC253P IL08 C-MOS 4-LINE-TO-1-LINE DATA SELECTOR/MULTIPLEXER —TOP VIEW— 1 ENX ENX IN 1 VDD (+2 to +6 V) 16 6 X0 5 X1 B IN 2 15 ENY IN 4 X2 XC 7 3 X3 X3 IN 3 14 A IN OPEN X2 IN 4 13 Y3 IN 14 A 2 B X1 IN 5 12 Y2 IN 10 Y0 X0 IN 6 11 Y1 IN 11 Y1 YC 9 12 Y2 XC OUT 7 10 Y0 IN 13 Y3 OPEN 8 GND 9 YC OUT 15 ENY CONTROL IN ON CHANNEL EN B A 0 0 0 0 0 0 1 1 0 1 0 2 0 : LOW LEVEL 0 1 1 3 1 : HIGH LEVEL 1 x x OPEN x : DON’T CARE