The First Widely Used Music Scheduling System

In 1979 Andrew Economos founded Radio Computing Services. RCS's first product was Selector, a music scheduling system.

"The original Selector was developed on a PDP-11/03 under RT-11 and was programmed in Fortran and FMS-11. The goal of Selector is to help music directors of radio stations to handle day-to-day operations such as daily schedule generation, maintenance of music library and format hours" (Wikipedia article on Radio Computing Services).