Stefan Wagner's DiskMaster64 Is a Compact, Low-Cost USB Adapter for Commodore IEC Floppy Drives
A more compact and lower-cost version of the DiskBuddy64, this adapter lets you read and write C64/C128 disks on real hardware.
Electronics hobbyist and vintage computing enthusiast Stefan Wagner has released a low-cost interface board designed to connect classic Commodore 5.25" floppy drives to modern PCs via USB: the DiskMaster64.
"The DiskMaster64 is a conversion of the DiskBuddy64 from the [Microchip] ATtiny to the [WCH Electronics] CH552 microcontroller," Wagner explains of his blend of modernity and history. "This makes the adapter even smaller, simpler, and cheaper while retaining its full functionality. The CH552E is a low-cost, enhanced E8051 core microcontroller compatible with the MCS51 instruction set. It has an integrated USB 2.0 controller with full-speed data transfer (12Mbit/s) and supports up to 64 byte data packets with integrated FIFO and direct memory access (DMA)."
In Wagner's project, the CH552E chip is used to bridge a modern USB connection to the Commodore IEC Bus, as used in various of the company's classic microcomputers for floppy disk and printer connectivity. As the name suggests, the DiskMaster64 concentrates wholly on the floppy disk element — allowing unmodified Commodore 1541 and compatible 5.25" drives to be connected to modern PCs.
"The DiskMaster64 is a proprietary interface and does not transform the floppy disk drive into a typical USB mass storage device," Wagner explains. "Instead, it allows you to communicate using low-level IEC commands over USB. Python scripts are provided to support this interface, enabling you to access the floppy disk drive and its contents directly. Thanks to the integrated fast loader, you can read or write floppy disks at 12 times the normal speed, allowing you to copy an entire disk in about 32 seconds."
For those comfortable at the command line, a Python-based tool allows for disks to be listed, formatted, read into a D64 image file, or an existing D64 image file written back to disk. For those who'd prefer it, there's a graphical user interface too — which includes shortcuts for flashing new firmware on the microcontroller or extracting individual PRG files from a disk. Wagner does, however, note that the device won't let you create images from copy-protected disks.
The project's hardware design and firmware are available on GitHub under the reciprocal Creative Commons Attribution-ShareAlike 3.0 Unported license; anyone with a stock of ATtiny devices, meanwhile, may prefer to build the earlier DiskBuddy64.