High-Performance Silicon-Gate CMOS The MC74HC139A is identical in pinout to the LS139. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LSTTL outputs. This device consists of two independent 1-of-4 decoders, each of which decodes a two-bit Address to one-of-four active-low outputs. Active-low Selects are provided to facilitate the demultiplexing and cascading functions. The demultiplexing function is accomplished by using the Address inputs to select the desired device output, and utilizing the Select as a data input.