The Fairchild Switch FST3257 is a quad 2:1 high-speed CMOS TTL-compatible multiplexer/demultiplexer bus switch. The low on resistance of the switch allows inputs to be connected to outputs without adding propagation delay or generating additional ground bounce noise.
When OE is LOW, the select pin connects the A Port to the selected B Port output. When OE is HIGH, the switch is OPEN and a high-impedance state exists between the two ports.