This part is a kind of semiconductor called 74155.
Function of this product has Dual 2-Line to 4-Line Decoders/Demultiplexers.
Manufacturers : National Semiconductor
Image and pinout :
Some of the text within the PDF file :
DM54155 DM74155 Dual 2-Line to 4-Line Decoders Demultiplexers February 1993 DM54155 DM74155 Dual 2-Line to 4-Line Decoders Demultiplexers General Description These TTL circuits feature dual 1-line-to-4-line demultiplexers with individual strobes and common binary-address inputs in a single 16-pin package When both sections are enabled by the strobes the common address inputs sequentially select and route associated input data to the appropriate output of each section The individual strobes permit activating or inhibiting each of the 4-bit sections as desired Data applied to input C1 is inverted at its outputs and data applied at C2 is true through its outputs The inverter following the C1 data input permits use as a 3-to-8-line decoder or 1-to-8-line demultiplexer without external gatin [ ... ]