Later judging from the microwave touch pads "Automatic Cooking Controls" which are identical to the ones on GE countertop mw which we bought new about 1984. Unless of course they were using those same design buttons for a long time before that,, don't think so.
Didn't Litton make a similar product also?
I imagine these were pretty popular as the first generation microwaves were pretty big. In a small kitchen, people would have to use carts to hold them as they took up too much counter space. This is much more convenient.
These things are top heavy, real pain to move. But, the design is great, saves space and the thing is immaculate. But goatfarmer is right, demand for these type of machines are nearly zero, think I've ever sold one. To the crusher it goes. Matt