820-2828 – Apple A1312
The 820-2828 (Apple) motherboard is found in the Apple A1312. The catalog lists 6 files for it: 4 BIOS files, 1 schematic and 1 boardview.
File names mention revision A. BIOS images are 8 MB. First posted in March 2021 in BIOS Archive, Schematics & Boardviews Archive and Cyberlan Electronics.
BIOS dumps 4
Schematics 1
Boardviews 1
Board facts
| Board number | 820-2828 |
|---|---|
| Numbering | Apple board number |
| Revisions | A |
| BIOS chip size | 8 MB |
| Flash chip | 25L6406E, MX25L6406E |
| First seen | 2021-03-14 |
| Source channels | BIOS Archive, Schematics & Boardviews Archive, Cyberlan Electronics |
| About the number | Apple logic boards are numbered 820-xxxx or 820-xxxxx; the trailing letter is the revision. |
Apple models for this logic board
| A-number | Model | Years |
|---|---|---|
| A1312 | iMac 27-inch | 2009–2011 |
A-numbers come from the file names; the model names and years are Apple's published identifiers.
Laptops that use 820-2828
What these files are for
A BIOS dump is a full image of the board's SPI flash chip. It is written back with an SPI programmer when the original firmware is corrupted, after a chip replacement, or to recover from a failed update. Read and save the original chip first: serial number, DMI data and the Intel ME / AMD PSP state differ between boards.
A schematic is the circuit diagram of the main board: power rails, power-up sequence, component values and net names. It is the reference for measuring voltages and tracing a fault.
A boardview is the component placement map of the PCB: click a part or a net and the viewer highlights where it is and what it connects to. Used together with the schematic to find test points.
Tools to open these files
| Format | What it is | Open with |
|---|---|---|
| .brd | .brd boardview (Test_Link format) | OpenBoardView, FlexBV or BoardViewer |
| PDF schematic | any PDF reader; Sumatra PDF and Foxit handle large schematics well | |
| .rar | RAR archive | 7-Zip or WinRAR |
| .zip | ZIP archive | 7-Zip, WinRAR or the built-in Windows extractor |
| .bin | BIOS image inside the archive (usually .bin) | a CH341A, XGecu T48 / TL866II Plus or RT809H programmer |
Questions
Is there a boardview for 820-2828?
Yes, 1 boardview file in .brd format.
Which laptops use the 820-2828 board?
Files in the catalog link 820-2828 to the Apple A1312.
What BIOS chip size does 820-2828 use?
The BIOS images for 820-2828 are 8 MB. Flash chips named in the files: 25L6406E and MX25L6406E.
Where do the download links go?
Each button opens the original public Telegram post the file was shared in. ChambersDesignInc.com only indexes and cross-references those posts.