BIOS / EFI firmware binary for the Apple logic board 820-00923, revision -05, packed in a 4.95 MB ZIP. Apple's 820- numbers name the logic board, and the suffix marks the revision, which should match the PCB. Technicians write images like this to the SPI chip with a programmer when a machine does not chime or boot because of corrupted firmware. Always read and archive the original contents first so serial and system data can be kept.
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 .zip file
Compressed archive that every operating system opens without extra software.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →