Catalogued as a schematic, this 75.7 KB PDF is called 2716 and offers no brand or board information in its name. The number is consistent with the early 27-series EPROM designation, though only the document itself can confirm it. Content of this sort lists pin functions, operating modes and programming data for a single memory chip. It helps when reading out or duplicating firmware from vintage equipment with a programmer; always store a dump of the original chip before attempting an erase or rewrite.
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.