This started out as the 2700 series. The backbone of the system was a base cabinet with a panel area to mount modules, plus an integrated keyboard and performance controls. One of the modules had to be a power supply, unless an external supply was available. At first the modules available were a VCO, an LFO, a non-resonant single pole low pass VCF, a bandpass VCF, a VCA, an AR envelope generator, and a buffer-inverter.