74HC/HCT153 is a high-speed Si gate CMOS device that is pin compatible with low-power Schottky TTL (LSTTL). It is specified in compliance with JEDEC standard no. 7A. The two 4-input multiplexer circuits have individual active LOW output enable inputs (1E, 2E) which can be used to strobe the outputs independently. When the corresponding output enable inputs are HIGH, the outputs (1Y, 2Y) are forced LOW. The “153” is the logic implementation of a 2-pole, 4-position switch, where the position of the switch is determined by the logic levels applied to S0 and S1. The logic level S0 is high, and S1 is low when the multiplexer selects the output from D0 and D1; the logic level S0 is low, and S1 is high when the multiplexer selects the output from D2 and D3; the logic levels S0 and S1 are both high when the multiplexer selects the output from D4 and D5.