The MC74HCT138A is identical in pinout to the LS138. The HCT138A may be used as a level converter for interfacing TTL or NMOS outputs to High Speed CMOS inputs. The HCT138A decodes a three-bit Address to one-of-eight active-lot outputs. This device features three Chip Select inputs, two active-low and one active-high to facilitate the demultiplexing, cascading, and chip-selecting functions. The demultiplexing function is accomplished by using the Address inputs to select the desired device output; one of the Chip Selects is used as a data input while the other Chip Selects are held in their active states.