The Farfisa Syntorchestra is an Italian analog keyboard/synthesizer from 1975. It was used by Klaus Schulze on his album Moondawn, by Ash Ra (Ashra Tempel) and by Vangelis.

Basically, it is a simple monophonic synthesizer with some presets which can be modified and a polyphonic section. These two sections can be also combined and slightly detuned (intervals are also possible) to sound like a 2-VCO monophonic synth. 

Resources:

• An overview of the Farfisa Syntorchestra
• Overview of the Farfisa Syntorchestra at SynthMania
• Farfisa schematics

video via AnalogAudio1