Apple logic board firmware for board 820-00138, labelled as a working, fully tested BIOS dump, packed in an 8.68 MB RAR archive. Apple identifies logic boards with 820-xxxxx numbers, and the suffix printed on the board identifies the exact revision. The dump is meant for rewriting the SPI flash with a programmer when a Mac fails to boot because of corrupted firmware. Keep a copy of the original chip contents, since it holds serial and configuration data, and verify that the image size suits the 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 →