74HCT257N (NEXPERIA)

The 74HCT257N is a 2-input Quad Multiplexer with 3-state output. This high-speed Si-gate CMOS device is pin compatible with low-power Schottky TTL (LSTTL). It has four identical 2-input multiplexer with 3-state outputs, which select 4 bits of data from two sources and are controlled by a common data select input (S). The data inputs from source 0 (1I0 to 4I0) are selected when input S is low and the data inputs from source 1 (1I1 to 4I1) are selected when S is high. Data appears at the outputs (1Y to 4Y) in true (non-inverting) form from the selected inputs. It is the logic implementation of a 4-pole, 2-position switch, where the position of the switch is determined by the logic levels applied to S. The outputs are forced to a high-impedance OFF-state when OE is high.