74157

74157 IC

The 74157 is a quad 2-line to 1-line multiplexer. Basically how this works is there are two inputs ( A and B ) for every output ( Y ). There are four groups like this, with two inputs and one output each. There is one select signal for the whole chip. When the select signal is low, the output ( Y ) is the same as input A. When the select signal is high, the output Y is the same as input B.

Pin	Function	Function	Pin
1	Select	Vcc	16
2	1A	15
3	1B	4A	14
4	1Y	4B	13
5	2A	4Y	12
6	2B	3A	11
7	2Y	3B	10
8	Gnd	3Y	9

Datasheet for 74157

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