 Integrating this technology into a synthesizer, Oberheim introduced the OB1, the first programmable monophonic synthesizer, in 1977.By 1980, Oberheim's products, by then including synthesizers, a polyphonic digital sequencer (the DSX), and a sampled-sound drum machine (the DMX) were designed to be combined to form a complete system, and could be interconnected by a proprietary Oberheim parallel bus interface that pre-dated MIDI.With the company now gathering pace, from the turn of the 1980s Oberheim now streamlined his polyphonic synthesizers into a series of major integrated keyboard instruments which proved highly popular, coming to define many records of the era, to a similar extent to Sequential's Prophet 5.