A 362 KB PDF datasheet whose file name, SDLS178, is a literature code without any part number. This numbering follows the scheme Texas Instruments uses for standard logic datasheets, so the device is most likely a logic family IC named on the first page. The document should list pin functions, switching characteristics and electrical limits. A repair technician uses such data to confirm a chip is powered correctly, to compare outputs against the function table, and to choose a pin-compatible replacement.
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.