PDF document, 134 KB, for the 23c040 part, catalogued among schematics. The 23C numbering is typical of mask ROMs, with 040 usually meaning 4 Mbit capacity, though the name does not identify the manufacturer. Inside one can expect the pin diagram, byte organisation, read timing and electrical characteristics. It helps when tracing address and data buses to the ROM, checking chip enable and output enable lines, or finding a pin-compatible programmable replacement. Confirm the package marking matches before relying on it.
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.