RAR archive, 781 KB, named only with the numeric code 321-1-4-01. No brand, device, revision or content type is stated, so treat it as unidentified until it is extracted and inspected. The code matches a series of similarly named files and is probably a board or document identifier. If the contents are a schematic, use it to trace power and signal paths. If they are a firmware image, verify that the chip size matches and back up the original before programming.
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 @cyberlanelectonik. 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.
7-ZipWinRARThe Unarchiver (macOS)