If you simply copy the c64 Romset at https://archive.org/details/C64Romset onto a USB stick and put it into the c64 Maxi/Mini, only the first 256 roms will be shown.
This Python 3 script splits the 17,083 folders from the c64 Romset into separate folders containing no more than 256 folders per folder. This enables the c64 mini/maxi to display all the roms in the Romset.
- Install Python 3
- Put the script into the folder containing the unzipped romset
- Launch the script.
The split roms will appear in the root directory of the drive, in a new folder: "c64Romset_output".