Apple firmware archive for a MacBook A1398 from 2015, logic board 820-00426, revision A, sized for an 8MB flash chip and marked as tested working. The 820- prefix is Apple's own logic board numbering, so compare the full number and revision on the PCB before use. Technicians typically extract the dump and write it to the SPI EFI chip with a programmer to fix boot or lock problems. Read and save the original chip contents first, and confirm the image size matches the 8MB part fitted.
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 →