
Click here for shots via this auction.
Update: Some interesting bits on the M500 just in via The Most Underrated Synth post.

They could afford 6 VCAs because, for a fixed-voice, fixed-envelope monosynth, they could get away with one-transistor VCAs and RC (NO active component) envelopes, and the VCF/VCA chip I imagine was used in other synths as well.
OMD used this synth a lot on their first few albums. You can recognize it easily in their stuff before they got into samplers, which you can also recognize (Dazzle Ships onwards)"