A BIOS / firmware dump. Shared as “B550MG.15a” — a .15a file, 32.0 MB.
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 @ShareMan_Electronic_Files. Enginerys does not host this file.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →