The Commodore 2031 and Commodore 4031 are single-unit 5¼" floppy disk drives for Commodore International computers. They use a similar steel case form to the Commodore 9060/9090 hard disk drives, and use the parallel IEEE-488 interface common to Commodore PET/CBM computers. Essentially, both models are a single-drive version of the Commodore 2040/4040 units.