PDF of about 539 KB named only with a Texas Instruments SDLS literature code, so the specific device is not given in the name. That series is normally used for TI logic datasheets, implying a 74-series TTL part, but the title page must be checked to know which. Contents typically include function tables, pin diagrams, recommended operating conditions and switching characteristics. After identifying the covered chip, use it for pin lookup and logic-level checks, matching the part number to the IC on the board.
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.