BIOS/EFI image for the MacBook Air A1466 on Apple logic board 820-00165-A, packed into a 4.21 MB RAR archive. Apple's 820-series numbers identify the logic board, with the trailing letter indicating revision. Technicians flash such dumps onto the SPI ROM with an external programmer to resolve no-boot conditions or firmware corruption. Dump the original chip first, because it carries serial data that should be transplanted into the new image, and check the board number printed near the CPU area matches.
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 →