The MC74VHC257 is an advanced high speed CMOS quad 2-channel multiplexer fabricated with silicon gate CMOS technology. It achieves high speed operation similar to equivalent Bipolar Schottky TTL while maintaining CMOS low power dissipation.It consists of four 2-input digital multiplexers with common select (S) and enable (OE)bar inputs. When (OE)bar is held High, selection of data is inhibited and all the outputs go Low.The select decoding determines whether the A or B inputs get routed to the corresponding Y outputs.The internal circuit is composed of three stages, including a buffer output which provides high noise immunity and stable output. The inputs tolerate voltages up to 7V, allowing the interface of 5V systems to 3V systems.