Firmware for a device identified as P660RU-T1v3s, with the tag 201512 suggesting a December 2015 build or dump. The model string matches the naming of ZyXEL P-660RU ADSL modems, version T1 v3s, though the name does not state the brand. The 1004 KB RAR likely contains the flash image used to recover a bricked unit via a programmer or bootloader. Confirm the hardware revision on the label, back up the original flash, and ensure the image matches the chip size.
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 →