The earliest floppy disks – developed in the late 1960s – measured 8 inches (200 mm) in diameter and first became commercially available in 1971.

Image Credit: Wikipedia
However, it wasn’t long before the 5¼ inch format displaced its 8-inch one predecessor for most applications, before itself being supplanted by 31⁄2-inch disks. According to Wikipedia, the advantages of the ubiquitous 3 1⁄2-inch disk were its smaller size and plastic case which provided improved protection from dust and other environmental risks.
Granted, it’s been quite a while since most of us have seen a floppy disc, especially in an age when DVDs and CDs are already perceived as quite dated. Yet, one can’t help being overcome by a wave of nostalgia when coming across a project utilizing the retired medium. Kiu’s (Simon Schoar) RumbleRail is one such example. As HackADay’s Brian Benchoff notes, the engineering and design quality that went into the build puts the device in a class by itself.
“Instead of the usual assemblage of wires, power cords and circuits that accompany most musical floppy drive builds, Kiu‘s is an exercise in precision and modularity,” he explained. “Each of the eight floppy drives are connected to its own driver with Atmel’s ATmega16 microcontroller (MCU) on board.”
More specifically, each floppy is driven by an ATmega16A-AU, while the “heavy lifting” of decoding MIDI files and driving the display is executed by an ATmega1284P-AU.
“The microcontrollers in these driver boards receive orders from the command board over an I2C bus,” Benchoff continued. “Since everything on the RumbleRail is modular, and the fact Kiu is using DIP switches to set the I2C address of each board, this build could theoretically be expanded to 127 voices, or 127 individual floppy drives each playing their part of a MIDI file.”
The RumbleRail is more than capable of operating in standalone mode without a PC. Indeed, MIDI files are loaded from an SD card and decoded by the main controller board.
Interested in learning more? You can check out the project’s official page here.
Each floppy is driven by an ATMEGA 16A-AU and the “heavy lifting” of decoding midi files and driving the display is done by an ATMEGA 1284P-AU.
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