Firmware image for the Apple logic board 820-2542-A, a raw 4 MB binary dump of the boot ROM. Apple's 820-xxxx numbers identify logic boards, and the letter suffix marks the revision. A dump like this is written to the SPI flash chip with an external programmer when a Mac shows no chime, a boot loop or corrupted firmware. Always read and save the existing chip before writing, because the original holds machine-specific data such as serial number and network address. The chip must be a 4 MB part for the image to fit.
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 @bioshub. Enginerys does not host this file.
How to open a .bin file
A raw, byte-for-byte image of a flash chip: the main BIOS / UEFI, the embedded-controller (EC) firmware, or both.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →