The 74HC251; 74HCT251 is an 8-bit multiplexer with eight binary inputs (I0 to I7), three select inputs (S0 to S2) and an output enable input (OE). The select inputs select one of the eight binary inputs and route it to the complementary outputs (Y andY). A HIGH onOEcauses the outputs to assume a high-impedance OFF-state. Inputs include clamp diodes that enable the use of current limiting resistors to interface inputs to voltages in excess of VCC.