Datasheet in a 106 KB PDF for the 27c256, a part number in the common 27C CMOS EPROM family, although the catalogue lists it as a schematic. The name carries no manufacturer, board or equipment model. Inside you can expect pin functions, operating modes, voltage limits and programming specifications. Those are what a repair technician needs to read or rewrite firmware with a universal programmer or identify a compatible substitute. Check speed grade and vendor on the chip, and save the original contents before erasing.
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.