Listed under schematics, this 92.0 KB PDF has a purely numeric name, 27256, with no manufacturer or revision attached. The number lines up with a well-known 27-series EPROM designation, though the file itself should be checked to confirm. Material of this kind normally covers pin assignments, read and program modes, and timing diagrams. It is useful when setting up a device programmer to read or rewrite a vintage parallel memory chip; always save a copy of the original contents before erasing or programming.
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 @cyberlanelectonik. 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.