The Prophet 5 was the first fully programmable polyphonic synth to hit the market. It raised quite a stir in the synth world when first shown at the '78 NAMM. The Prophet 5 was revised several times before the design was retired in the early '80s. I personally prefer and own a Rev 2. The Prophet 5 features a nicely finished maple and aluminum case sporting a 61 note keyboard with pitchbend and modulation wheels, and an array of external CV inputs. The Rev 1 & 2 had 40 patch memories, while Rev 3.2 and later had 120 memories. Each patch stores all data for the two multi-waveform oscillators, VCA, VCF, associated envelopes, LFO, and polymod section. The second VCO's keytracking can be turned off to allow use as a second LFO, and the polymod section has several interesting modulation destinations, including VCF cutoff. I was really disappointed that although SCI provided the P5 with a noise source, they did not provide a sample and hold. The unit can be easily modded to accommodate a S&H, and I'm sure mine will see this mod in the near future. Only the P5 Rev 3.2 and 3.3 came with factory MIDI. The Rev 1 & 2 can be retrofitted with a Kenton MIDI kit, but like all Kenton kits, it's a real hack. The Kenton kit (installed in mine) provides for note on/off, sustain, and mapping of aftertouch and modulation to VCA, VCF cutoff, and VCF resonance. The Rev 1 & 2 both used SSM ICs for oscillators, filters, and VCAs while the Rev 3s used CEM chips exclusively. Neither Rev 1s nor Rev 2s had particularly healthy power supplies, but the Rev 2 did have a revised voice board which was slightly more stable. It's not uncommon for Rev 2s to need power supply work, often consisting of nothing more than replacement of the voltage regulators with higher current devices. revision  production  serial numbers  ICs  patches  new features   1.0        1978       0000-0182     SSM    40   2.0      1978-80      0183-1299     SSM    40     tune and edit buttons   3.0      1980-82      1300-         CEM    40   3.1        1982                     CEM    40     instant editing   3.2        1982                     CEM  40/120   seq interface, some w/midi   3.3      1982-84                    CEM    120