The CD54AC257/3A and CD54ACT257/3A are quad 2-input multiplexers with three-state outputs. These devices utilize the Harris Advanced CMOS Logic technology. Each of these devices selects four bits of data from two sources under the control of a common Select input (S). The Output Enable (OE) is active LOW. When OE is HIGH, all of the outputs (Y) are in the high-impedance state regardless of all other input conditions.