ASUS UX305CA BIOS file with a .300 extension, 8.00 MB in size, a format typical of ASUS firmware updates where the extension reflects the BIOS version, here apparently 300. As an update capsule it may carry a header and may not be a direct chip image. Use EZ Flash for normal updates, or extract the body before writing with a programmer. Check the model matches, back up the existing chip, and confirm the result fits the 64 Mbit flash.
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 @biosfilebins. 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 →