A 122 KB PDF named 23c512, filed as a schematic though the name indicates a component document for a part numbered 23C512. In common numbering the 23C prefix is associated with mask ROM memories, and 512 usually reflects the capacity in kilobits, but the file should be read to confirm. A technician uses such a sheet for pinout, organisation and timing when identifying a ROM on an older board or matching it to a programmable replacement. Check the marking on the chip against the document before acting 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.