A BIOS / firmware dump for Apple hardware (board 820-3662). Shared as “Macbook_820-3662-a_(Luirons_Bios).rar” — a .rar file, 4.51 MB.
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 @Satale_bios_esquemas_Laptop. 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.
7-ZipWinRARThe Unarchiver (macOS)
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →