Walter,
Your date of 1982 for the first Kn board has me a bit puzzled. Way back in 1978 I attended a demonstration concert given by Alan Haven on then new JVCM1210 organ. A superb player and a brilliant organ for the time. At the interval, the presenter who was from Technics (which made me assume at the time that the JVC was a Technics product under another name) came on stage with a keyboard which was suspended from a strap over his shoulders rather like an accordion(so it must have been pretty lightweight). The accompaniments and sounds coming from this instrument were amazing (again for the time) and when the Technics man finished the instrument was placed on a stand at right angles to the organ and Haven played piano from it while playing the organ.
I don't think JVC ever produced another organ, but the point of my rambling is, would 1978 not have been the year of the first Technics keyboard?

Peter