The ZoomFloppy is a fast and inexpensive USB floppy interface designed by Nate Lawson which connects Commodore 15×1 or PET floppy drives to your PC. Notably, it supports the nibtools protocol for backing up protected disks.
From Jim Brain’s Retro Innovations website:
ZoomFloppy comprises a circuit board containing an Atmel ATMEGA32U2 microcontroller and support circuitry. The ZoomFloppy interface includes on board ports for IEC-based disk drives, connectors for the various Commodore drive parallel cabling systems, and IEEE-488 connectors for future expansion capabilities. The entire unit can be installed in a standard Hammond plastic enclosure for a truly professional look. A mini-USB port provides power and PC connectivity.
The ZoomFloppy can copy real Commodore disks to D64 images suitable for use in VICE and other emulators. It can also take a D64 image and write it out to an actual floppy disk. This should be useful for creating archival copies of old floppies which are now reaching the end of their usable life.
ZoomFloppy also provides DB15-M, a 2×8 header, and a 12/24 .156″ connector for parallel cable connections which provide improved speed and the ability to utilize Nibtools. XAP1541-compatible cables will plug into the DB15 connector, while old user port cables can connect to the 12/24 edge connector on the board.
In its most basic use case, the Commodore 15×1 drive is connected via a standard Commodore IEC serial cable to the IEC port on the ZoomFloppy and the PC is connected via the Mini-USB connector. You can then use OpenCBM (or something similar) to control the 15×1 drive directly from the PC.