Microchip 25AA160A/B and 25LC160A/B serial EEPROMs are the subject of this 522 KB PDF, filed as a schematic but best treated as a datasheet. These are 16 Kbit SPI parts, and the A and B suffixes refer to page or organisation variants that the document explains. Look here for the pin assignments, write-protect behaviour, status register and electrical limits. A repair technician uses it to pick the right device profile in a programmer and to verify supply, clock and chip select signals before suspecting the chip itself.
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.