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. Currently it emulates a RAM Expansion Unit up to 16mb (compatible to CBM 1700/1750/1764 REU, CLD Super 1750 Clone, CMD 1750/1750XL) and a GeoRAM/NeoRAM memory expansion up to 4mb. It also features a menu to browse, manage and launch REU- and GeoRAM-images, NUVIEs, and PRGs. The RAD is designed to not only emulate existing extensions, other things that have already been tested (but not yet included here) are, for example, MOS 6510/8500 emulation (incl. turbo mode) or using the RAD as a (co-)processor (in fact the menu runs on the ARM CPU only).