With programmability of sounds being a feature of the Four-Voice, Eight-Voice, and OB-1, musicians needed a way to backup the programs they created in some way. The Oberheim Cassette Interface could be connected to an FVS-1, and EVS-1, or an OB-1 through a multi-pin Molex connector in order to save the stored program data onto audio cassette tapes. This capability was built into later Oberheim synthesizers beginning with the OB-X, making the CASS-1 no longer necessary.