When a software package is split into multiple parts (like part1.rar , part2.rar ... part5.rar ), it is usually because the total file size was too large for a single upload. To successfully extract the toolchain:

: You must download every single numbered part (Part 1 through Part 5) into the same folder on your computer.

: Ensure the filenames are identical except for the part number (e.g., RT809F_English.part1.rar ).

How to Install RT809F Programmer Software and Toolchain Full Setup