Once upon a time, there was no such thing as a Theatre Management System. Content management consisted of carrying reels from booth to booth, and monitoring playback meant looking through the porthole to check everything was working. But then, of course, along came digital cinema, and with it the need to deal with multiple content files, as well as a multitude of KDMs.
Source: Making the Connection: The TMS is dead, long live the TMS! | Film Journal International