MS-50 Monophonic Synthesizer
(from a magazine ad)

Patch system expansion unit with independent
modules for complete programming flexibility.

Equipped with a range of modules you would expect to find on a studio
type synthesizer, the MS-50 includes VCO, VCF, VCA, two envelope
generators, voltage controlled modulation generator, 3-channel DC
voltage mixer (adding amp), ring modulator, divider, integrator, inverter,
and sample & hold. All connections are made externally via the complete
patch system to give you unrestricted control.