A polyphonic analog synthesizer introduced by Moog in 1981; it was one of the last designs created by the original Moog Music. The Memorymoog, as the name implies, had patch memory with 100 slots. It was six-voice polyphonic, with a fairly standard VCO-VCF-VCA processing chain.
Unusually, the Memorymoog had three VCOs per voice, one of the few polyphonic synths to be so equipped. It allowed VCO 3 to be used to frequency modulate the other VCOs, in addition to a dedicated LFO. Voices could be stacked on notes, up to unison -- an amazing 18 oscillators on one note! The Memorymoog is regarded as having a very thick and beefy sound, in part due to the ability to stack a large number of VCOs on a note.
Unlike most Moog products, the Memorymoog did not use a Moog-designed VCO; in order to simplify the design and save space, it used the Curtis 3340 VCO IC. It did, however, have traditional Moog transistor ladder VCFs. Note priority was selectable, and an arpeggiator was included. There were also several choices of gating modes for the envelope generators.
Unfortunately, the Memorymoog quickly gained a reputation as an unreliable synth. With 18 oscillators, it badly needed an auto tune function that worked properly, but as originally designed the auto tune could only "capture" a VCO if it was very close to being in tune already, and frequently one or more VCOs failed to tune when the auto tune ran. The original noise source was a pseudo-random number generator whose sequence was too short, and produced audible noise clocking. Moog used poor quality connectors for the cables that connected boards together, and some of the trim pots were also substandard.
To correct some of the problems, and add MIDI capability, Moog introduced the Memorymoog Plus. This version corrected most of the auto tune problems, fixed some bugs in the operating system, and added a very basic MIDI capability as well as an onboard sequencer. It didn't remain in production very long as all synthesizer production ceased in 1985. Since then, several aftermarket makers have offered upgrades; notable among them is the Lintronics Advanced MemoryMoog (LAMM), which replaces all of the trim pots and connectors, in addition to installing a totally rewritten operating system with very advanced MIDI capability.
Today, Memorymoogs are highly valued on the used market, despite the reliability problems. Part of the reason for the high value is simply that not many remain in usable condition, but the basic design is regarded as one of the original Moog's better efforts.