The Jupiter 4 is a difficult one to sum up. In real terms its a lovely sounding, relatively flexible 4 oscilator analog monosynth. It was heavily used from around 1979-1982 on pop tracks (Duran Duran 'Rio' random arpegio - Depeche Mode 'Just Can't Get Enough' lead riff) etc etc
To be honest, Ive never used one or owned one. It does sound great.....but I prefer Pro-One's and Mono-Poly's.
Heres a clip or two to get an idea
JUPITER 4 EXPERIMENT
Sorry I cant help further
DS