RubyDrive - Motorola 68000 (and Mega Drive) emulator in Ruby
RubyDrive is a pure-Ruby emulator of Motrola 68000. The intention is also to support Mega Drive peripherals and Video Display Processor, to support Mega Drive software. However, it is not intended to be fast enough to play Mega Drive games.
It is still at an early stage but it can run some instructions.
The git repository is available at GitHub.