BIOS (EFI firmware) dump for an Apple model A1347, the Mac mini, on logic board 820-5509-A, where the trailing letter is the board revision. The 3.81 MB RAR holds an image intended for the SPI flash on the logic board, written with a programmer such as a CH341A or RT809. Apple's 820-xxxx numbers identify the logic board itself, so match the number on your board rather than the model alone. Back up the original chip first, since it holds the serial number and other machine data.
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 →