This is a Casio's CT 6000 flagship model from 1984, and it's a very unusual beast for its time as it had a ton of high level features. For instance, it has MIDI, a velocity AND after touch keyboard, Unison modes, lush choruses, a complex  accompaniment section including "Super Accompaniment" that adds fills depending on how the person is playing, a pitch bend wheel with glissando control, and the ability to split and layer the keyboard. These were all rather advanced for a 1984 home keyboard and were not evident in any of Casio's other commercial keyboards up to 1984.