Original BIOS dump for the Apple logic board 820-01700-A, compressed as RAR and 2.34 MB in size. Apple 820-xxxxx numbers identify the logic board itself, and the A suffix is the revision, so check both against the silkscreen. A clean firmware image is used to reflash the SPI flash chip with a programmer after corruption or to clear a locked chip. Always read and keep the board's own contents first, because the image may carry serial or other machine-specific data, and confirm the size suits the fitted chip.
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 @biosarchive. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →