It’s small, got mini keys, an onboard speaker and only a single VCO, but don’t let any of that put you off because the 1984 released Yamaha CS-01 is a great little fun synth which, while designed as a very entry level instrument for budding synthesists, thanks to a decent tone and the inclusion of VCF and VCA control via a Breath Controller, is a genuinely expressive little analogue instrument.
Keytar lovers will also warm to the CS-01, thanks to the tabs allowing you to connect a guitar strap, plus the pitch bend (up only) and modulation controls being placed in a keytar-friendly position.
Essentially there were two versions of the CS-01 made, the earlier grey model has a 12dB filter while the MkII black model, released in 1984, contains a 24dB filter. Besides that, the only differences between the models are a adjustable resonance slider on the MkII as opposed to a two selection switch on the MkI.
Its feature set may be limited via the single VCO, Single ADSR and single LFO sine waveform but in the right hands the CS-01 remains a brilliantly expressive tool as demonstrated by Jean-Philippe Rykiel here:
Below is a short track with the CS-01 alongside an EMS Synthi AKS.