I had to go through my small MC collection, I don't think I've seen the one on the bottom before, it looks like it's marked an RN-Z580? If I had to guess it's mono only. 1981
Found this at an online market. Paied 8€, it is in perfect conditions, both working than aesthetics. Still in its original box with soft pouch and user manual. Only issue I found is noisy motor, but maybe it has always been like this. The servo assisted keyboard is interesting but I prefer mechanical controls.
The soft touch is nice, my high end models all have it and they were much more expensive than mechanical.
A very rare OTTO RD-XM1 . I've been looking for this model for a long time and I finally got lucky))). They are very expensive now. Sold for $3,000 at auction in Japan.
I try to return each device from my collection to factory condition, I spent 3 days on OTTO and now I am satisfied with the result. There is a new Fisher CR-M500 in the collection and now they play the same way.