The Roland Alpha Juno 1 is an analog polyphonic synthesizer manufactured between 1985 and 1986. It features one Alpha Dial that controls multiple parameters, as well as MIDI In, Out, and Thru functionality. It is well know for its use of digitally controlled oscillators in conjunction with analog filters. The Alpha Juno 1 is famous for the "hoover" sound used in early 90's techno. It is a very distinctive sound and hard to reproduce on other synths.
Watch some old Prodigy videos and you might see this synth on stage.