The RAD Expansion Unit is a cartridge expansion for the C64 and C128 using a Raspberry Pi 3A+, 3B+ or Zero 2 to implement the actual functionality. Besides running DOOM, that's emulating a REU up to 16 MB, and GeoRAM / NeoRAM memory expansions. It now got a new friend, the IECBuddy: an external disk drive and printer emulator. The IECBuddy can be used to synchronize files with the RAD and is integrated into its menu.

RAD Expansion Unit