Instruction: What are Roland's most famous synthesizers and drum machines from the 1980s and what do they do?

Response: The most famous Roland synthesizer and drum machines from the 1980s are the Roland TB-303, TR-606, TR-808, and TR-909. Although all were generally commercial failures at first, the TB-303 Bass Line became widely used in techno because of its distinctive resonant filter, beginning with Phuture's "Acid Tracks". The TR-606 Drumatix was also later widely used in electronica. However the TR-808 Rhythm Composer's booming kick and snare sound were even more popular, appearing widely in hip-hop tracks. The TR-909 was and is widely used in dance and pop music, known for its signature snare and hi hat cymbal sounds.