Small 27.9 KB PDF listed as a schematic and named 27LV256-20IL, a part code for a low-voltage 256 Kbit EPROM. The suffix appears to encode a 200 ns speed grade and industrial temperature range, with the final letter likely denoting the package, though the name names no vendor. Expect pinout, supply range and read timing. Useful when reading an EPROM with a programmer or sourcing a replacement. Confirm the package and marking on the chip, and note that UV-erasable parts need erasing before reprogramming.
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.