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

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.