Firmware archive for the P-660RU-T1v3, a model string in the style of ZyXEL ADSL modems; note this is the v3 revision, not v3s, and the brand is not given in the name. The 1002 KB RAR should contain a flash image for recovering a unit after a failed update. Hardware revisions are not always interchangeable, so check the device label carefully. Read and keep the original flash contents with a programmer, and confirm the image size fits the installed chip before writing.
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 @afsbiosfree. 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.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →