The RAD Expansion Unit can replace the CPU of your Commodore C64/C128 and run Doom, including colour reduction, sound streaming, mouse and MIDI-interfaces (PAL).
The features are: 50 fps, 22050Hz sample playback using the SID (MOS6581/8580/SIDKick) or Digimax, special modes for TFT displays, game-music via MIDI (Datel/Sequential interfaces) and Digimax sound output.


A Youtube video with a demonstration of DOOM on the C64.