PDF of 119 KB named 27C256B, filed as a schematic yet clearly a part number from the 27C CMOS EPROM line, here with a B revision letter. No laptop, board or brand is named in the file. Typical contents are pinout, DC and AC characteristics, programming flow and package drawings. Technicians use those to set up an EPROM programmer correctly or verify a replacement. Revision letters can change programming details, so match the chip marking exactly and back up the original data first.
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.