via this auction
You can find a demo of one here.

The Siel EX8500 is a polyphonic synthesizer with voice assignement containing 8 complete and individual synth modules (termed voices or channels). The instruments is provided with:
- 8 Oscillators (D.C.O.)
- 1 Pink Noise Generator
- 9 V.C.A.'s (8 for the DCO's and one for the noise generator)
- 1 24db / octave low pass Voltage Controlled filter (V.C.F.)
- 9 digital envelope generators (D.E.G.)
- 2 low frequency oscillators (L.F.O.)
- 1x SSM 2045 resonant low-pass filter (Sequential Circuits type filter)
- Analog Chorus (bbd based)
- Sequencer (polyphonic, 300 note)
- Full MIDI implementation
- Mono and Stereo outputs"