Microsoft Surface BIOS firmware for an i5 model with 128 GB storage, identified by the code M1086841-003, packed as RAR at about 3.5 MB. The name does not state the exact Surface generation, so compare the code against the label on the logic board. Such images are flashed to the SPI chip with an external programmer when the device fails to boot due to corrupted firmware. Keep a full backup of the original chip before writing, and make sure the dump size matches the flash chip, otherwise it will not fit.
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 →