74157

The 74157 (variants 74LS157, 74HC157) is a 74-series logic IC with four 2-input multiplexers sharing a single select line.

74157 Pinout

       .--\/--.
  S -> |01  16| -- +5V
1I0 -> |02  15| <- /E
1I1 -> |03  14| <- 4I0
 1Y <- |04  13| <- 4I1
2I0 -> |05  12| -> 4Y
2I1 -> |06  11| <- 3I0
 2Y <- |07  10| <- 3I1
Gnd -- |08  09| -> 3Y
       `------'

Signal descriptions

If /E is high, then all 4 Y output pins output as low, otherwise, if S is low, for each set of pins starting with the same number, Y is equal to I0, otherwise, if S is high, then Y is equal to I1.

Function table (L/H/X = low/high/irrelevant):

/E	S	I0	I1	Y
H	X	X	X	L
L	L	L	X	L
L	L	H	X	H
L	H	X	L	L
L	H	X	H	H

References

• TI - SN74LS157