The Commodore 65 was the intended successor of the Commodore 64.
The Commodore 65 was cancelled before it made it to release. There were however, several prototypes made, some of which still survive to this day.
It was a development of the Commodore 64C, bearing some similarities in the case design, but would have offered many advancements. One of which is the built in floppy disk drive. It also incorporated a new operating system unlike that of the Commodore 64 or Commodore VIC-20.
Tech problems\design errors
- A very small number of Ebay listings have appeared relating to prototypes of the Commodore 65.