===== 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.

{{chips:74157.gif?nocache }}
^ IC 1 ^^^^
^ Pin ^ Function ^ Function ^ Pin ^
|  1 | Select  |  Vcc | 16 |
|  2 | 1A  |  CE | 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  | 

==== Uses ====
  * [[controls:megadrive_genesis_controller_3|Genesis/MD 3-button controller]]
  * [[controls:pc_engine_controller|PC Engine/TurboGrafx 16 controller]]
  * [[http://www.gamesx.com/importmod/sat_switchless.htm|Saturn switchless import mod]]