A BIOS / firmware dump. Shared as “DAHUA 4 CH XVR 5104 HS DH9920C”, 16.0 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 @tvsoftwareworld. 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 →