PDF datasheet for the SN74S240N from Texas Instruments, an octal inverting buffer and line driver with three-state outputs in the Schottky TTL family, supplied in the N plastic DIP package. The 21.3 KB file is compact, probably a short summary rather than the full family datasheet. Repairers use it to identify the two output-enable inputs and the inverting channels when tracing address or data buses on older boards. Confirm the exact suffix on the chip, because non-inverting relatives such as the 244 share the same footprint but behave differently.
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.