Erkki Kurenniemi's On-Off was the first work to come out of the University of Helsinki's electronic music studio, 50 years ago in 1963. Kurennimei, a musical instrument inventor and composer (although he thought of himself as the former), built the studio as an unpaid volunteer.
The piece has been released a number of times, notably on the Rules compilation, and recently as a cassette on Ektro imprint Ruton Music, which collects three versions of the track (above).
As well as the original, the cassette includes an eight minute German edit, titled Ein-Aus, which is a mystery. Kurenniemi can't remember why it was made, or who for, bar "the Germans". The 2013 version of On-Off is by Finnish academics and analog synth players Mikko Ojanen and Aku Raski. It slices the original into 45 pieces, which have been sequenced to play in a random order.
Erkki Kurenniemi: 50 Years On-Off is released by Ruton Music, in a run of 200 copies. It is reviewed in the Soundcheck section of The Wire 351. More details on the release here.