The chromatone musical keyboard seen here replaces the conventional piano style keyboard with what’s known as a Jankó keyboard, a solution that dates from 1882. The result looks like a bizarre marriage of a musical keyboard and typewriter. In fact there are 312 unlabelled keys. The concepts can get a bit complex but in essence the main idea was to preserve the same structure for all chords and allow access to multiple incidences of the same notes without having to span the same distances required on a conventional musical keyboard layout.
Like many innovative ideas that take on an already established system it continues to face problems in gaining anything other than a niche acceptance owing to having to relearn a new system and is best exploited by those learning the system before or alongside a conventional system as this video shows.