Throughout the 1970s, legendary American composer Terry Riley toured regularly in Europe, performing solo organ concerts. In October 1978, Riley's personal technician Chester Wood built a stereo digital delay out of an ancient computer he had procured from Don Buchla, and the subsequent tour was the maiden voyage to try it out. Riley's specially modified two-manual Yamaha YC-45D portable combo organ had a Just Intonation setting and allowed him to feed stereo signals to the digital delay. The Yamaha had been manufactured with single mono output, but now with the modification it had a separate output for each manual eventuating in four channels (two live and two delayed).