Boot ROM firmware for an Apple iMac model A1419, EMC 3070, with logic board 820-01134-A, contained in a 4.28 MB RAR. The A1419 is the 27-inch iMac, and the EMC number narrows down the exact generation. The 820 prefix is Apple's logic board numbering, with the A suffix as revision. Use the dump with an SPI programmer to restore a board whose ROM is damaged. Back up the existing chip first, since it holds the serial number and other unit-specific information. Make sure the image size equals the flash capacity.
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 →