Under the name 27c040 this 153 KB PDF covers a part from the 27C CMOS EPROM series, even though it is categorised as a schematic. There is no board number, brand or device in the name. The sheet should provide the pinout, package outline, read timing, and VPP and programming algorithm details. A programmer needs those to handle the chip safely. It is useful for archiving or restoring firmware on older hardware. Compare the full part marking, including suffix, with this document before use.
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.