This part is a kind of semiconductor called 74HC138A.

Function of this product has 1-OF-8 DECODER / DEMULTIPLEXER.

Manufacturers : Motorola

Image and pinout :

Some of the text within the PDF file :

MOTOROLA SEMICONDUCTOR TECHNICAL DATA 1-of-8 Decoder/Demultiplexer High–Performance Silicon–Gate CMOS The MC54/74HC138A is identical in pinout to the LS138. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LSTTL outputs. The HC138A decodes a three–bit Address to one–of–eight active–low 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. • Output Drive Capability: [ ... ]

74HC138A PDF Datasheet Download