820-2855 – Apple A1370
The 820-2855 (Apple) motherboard is found in the Apple A1370. ChambersDesignInc.com has indexed 4 files for this board — 2 BIOS files, 1 schematic and 1 boardview.
File names mention revision A. BIOS images are 8 MB. First posted in June 2020 in Schematics & Boardviews Archive, Cyberlan Electronics and BIOS Archive.
BIOS dumps 2
Schematics 1
Boardviews 1
Board facts
| Board number | 820-2855 |
|---|---|
| Numbering | Apple board number |
| Revisions | A |
| BIOS chip size | 8 MB |
| Flash chip | MX25L6406D |
| First seen | 2020-06-07 |
| Source channels | Schematics & Boardviews Archive, Cyberlan Electronics, BIOS Archive |
| 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 |
|---|---|---|
| A1370 | MacBook Air 11-inch | 2010–2011 |
A-numbers come from the file names; the model names and years are Apple's published identifiers.
Laptops that use 820-2855
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
What BIOS chip size does 820-2855 use?
The BIOS images for 820-2855 are 8 MB. Flash chips named in the files: MX25L6406D.
Which laptops use the 820-2855 board?
Files in the catalog link 820-2855 to the Apple A1370.
Is there a boardview for 820-2855?
Yes, 1 boardview file in .brd format.
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.