Zip archive for the Apple logic board 820-01041, 2.63 MB. Apart from the board number, the name gives no Mac model, revision or file list, so open it to see whether it holds a schematic, a boardview or both. Apple marks its logic boards with 820-series numbers, printed on the PCB, and that number is the reliable way to match documents to hardware. Such files help with tracing power rails, finding the faulty component behind a short and following signals. Boardview files usually open in OpenBoardView or FlexBV.
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 @notebookschematic. Enginerys does not host this file.
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Compressed archive that every operating system opens without extra software.