54ACT253 Datasheet, National Semiconductor

n ICC and IOZ reduced by 50% Logic Diagrams IEEE/IEC DS100285-1 DS100285-2 Pin Names I0a
  –I3a I0b
  –I3b S0, S1 OEa OEb Za, Zb Descriptio.

The ’AC/’ACT253 is a dual 4-input multiplexer with TRI-STATE outputs. It can select two bits of data from four sources using common select inputs. The outputs may be individually switched to a high impedance state with a HIGH on the respective Output.