Firmware for the Apple MacBook A1312 logic board 820-2733 revision A, provided as a 1.61 MB RAR. A1312 is a 27-inch iMac model number, so check the hardware against the 820 board number rather than the product name. The image is used to rewrite the boot ROM on the SPI flash when the machine fails to start. Read and back up the original chip with a programmer first, confirm the image size matches the chip, and note that serial data may need restoring.
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.
All sources (10)
The same file was posted more than once. If one link is dead, try the next.
| Channel | Posted | |
|---|---|---|
| @biosarchive | 3 Apr 2020 | Open file on RM Schematics |
| @laptexlaptopbios | 8 Jul 2020 | Open file on RM Schematics |
| @one5technology | 21 Nov 2020 | Open file on RM Schematics |
| @pepeelectronica | 21 Apr 2022 | Open file on RM Schematics |
| @pepeelectronica | 24 Apr 2022 | Open file on RM Schematics |
| @skclappybios | 10 Apr 2024 | Open file on RM Schematics |
| @schematics_bios | 24 Jul 2026 | Open file on RM Schematics |
| @schematics_bios | 24 Jul 2026 | Open file on RM Schematics |
| @schematics_bios | 27 Jul 2026 | Open file on RM Schematics |
| @schematics_bios | 1 Aug 2026 | Open file on RM Schematics |
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 →