PDF datasheet for the 93C75A serial EEPROM, part of the 93-series three-wire Microwire memory family, filed under schematics with a size of 395 KB. The name does not state the manufacturer, so vendor-specific details such as voltage range and package options should be taken from the document. Technicians use such sheets to identify the chip select, clock, data in and data out pins and the organisation setting before reading the memory in circuit or on a programmer adapter, keeping a copy of the original dump.
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.