The Commodore 2031 and Commodore 4031 are single-unit 5¼"

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...

drives for

Commodore International Commodore International Corporation was a home computer and electronics manufacturer with its head office in The Bahamas and its executive office in the United States founded in 1976 by Jack Tramiel and Irving Gould. It was the successor compan ...

computers. They use a similar steel case form to the Commodore 9060/9090

hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...

drives, and use the parallel

IEEE-488 Glycoprotein Ib (GPIb), also known as CD42, is a component of the GPIb-V-IX complex on platelets. The GPIb-V-IX complex binds von Willebrand factor, allowing platelet adhesion and platelet plug formation at sites of vascular injury. Glycoprotein ...

interface common to Commodore PET/CBM computers. Essentially, both models are a single-drive version of the Commodore 2040/4040 units. The Commodore 2031LP is functionally the same as the 2031, but used the lower-profile tan case of the second version of the Commodore 1540 floppy disk drive intended for

home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...

use. These drive models use a single-density, single-side floppy data storage format similar to that used by the Commodore 1540 &

Commodore 1541 The Commodore 1541 (also known as the CBM 1541 and VIC-1541) is a floppy disk drive which was made by Commodore International for the Commodore 64 (C64), Commodore's most popular home computer. The best-known floppy disk drive for the C64, the ...

drives, but with a slightly different data marker indicating which model originally formatted the disk. The low-level disk format is similar enough to allow reading between models, but different enough that one series of drive models cannot reliably write to disks formatted with one of the other model series. A difference of one extra 'header' byte is what causes this write incompatibility.

References

Further reading