This is the Marina64, a new 1MB banked ROM cartridge for the Commodore 64, Commodore 128 and SX-64.
It’s based on the Magic Desk cartridge which was a Commodore product back in 1983 which was an early attempt at a desktop operating system. With a literal desktop graphic.
There was a file manager, calculator, and a very strange word processor that was like a virtual typewriter simulator where as you typed, the page of text moved to the left, creating a document 80 characters wide on a 40 column screen.
This didn’t catch on and was superseded by GEOS. However, it lives on in the hardware that was used. To learn more read the full article on Tynemouth Software Blog