At ECCC 2010, I presented these slides on the ZoomFloppy, a new device for accessing Commodore floppy drives from a PC via USB. The firmware, known as xum1541, has been available since fall 2009 for those who want to build their own board, but the ZoomFloppy is the first device that will be a complete product offered for sale. Jim Brain will be manufacturing and selling it by the end of the year.
The ZoomFloppy has a number of features beyond simple disk access, which is implemented in OpenCBM. It can also nibble protected disks using a parallel cable and nibtools. It is software-upgradeable and this presentation discusses some features that are planned for the future.
One surprising finding I made was that by running the 1571 drive in double-clocked (2 MHz mode), the hardware UART is just fast enough to enable transfer of raw bits, directly off the media. No one has every created a copier that took advantage of this “hidden” mode in the 25 years since the 1571 was introduced. Normally, this kind of transfer requires soldering a parallel cable into your drive. This mode works via the normal serial cable, but requires low-latency control of the bus that is only possible with a microcontroller (not DB25 printer port).
I also discuss how modern day piracy on the PS3 affected our chip supply and digress a bit to discuss old copy protection schemes. I hope you enjoy the presentation.