ZIP archive of 3.33 MB for the ASUS X550JX, where the trailing 204 most likely denotes BIOS version 204 under ASUS naming conventions. Unpack it and check whether the binary is a raw dump or an official capsule file with a header, because capsule files usually need conversion before burning with a programmer. Match the board revision on the PCB to the source, and back up the original SPI chip to keep device-specific data intact.
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 @biosbigarchives. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →