Zipped BIOS dump for Apple logic board 820-00928, with the A suffix in the name, about 5.07 MB compressed. Apple 820-numbers identify the logic board, and the number on the PCB must match before you flash. This kind of image is written to the SPI flash with an external programmer to revive a board with corrupt firmware. Read and save the original chip first, since Mac firmware stores serial number and other unique data, and make sure the extracted image matches the flash chip size exactly.
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 →