#74LS398

Description: Quad 2 to 1 line Multiplexer, 3-state outputs

Datasheet: http://www.ti.com/lit/gpn/sn74LS398

Pinout:

      +-----------+
    S |[ 1]   [20]| VCC
   QA |[ 2]   [19]| QD
~{QA} |[ 3]   [18]| ~{QD}
  I0A |[ 4]   [17]| I0D
  I1A |[ 5]   [16]| I1D
  I1B |[ 6]   [15]| I1C
  I0B |[ 7]   [14]| I0C
~{QB} |[ 8]   [13]| ~{QC}
   QB |[ 9]   [12]| QC
  GND |[10]   [11]| CP
      +-----------+