Texas Instruments literature code SDLS131 in a 339 KB PDF datasheet. The name does not identify the logic part, so open it and confirm the device listed on page one. The SDLS series is TI's archive of legacy TTL datasheets. These documents supply pinouts, function tables, maximum ratings and propagation delays that help when tracing signals or choosing a substitute IC. Make sure the part number and package on the PCB match the document before relying on its pin assignments.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet_technar_org. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.