cze 132022

After a long time it’s time for a big upgrade of my computer hardware orchestra. Here it is! The bigger and better Floppotron 3.0. 512 floppy disk drives, 4 scanners and 16 hard disk drives.

My noise-making contraption grew a little bit since last update. It has its own „studio” space and became a relatively complex device. There is a ton of cables, a lot of custom electronic circuits, but the whole power is in the firmware which has been rewritten from scratch. In this article I’ll try to explain the principle of operation, how it’s built, how the whole system works, what’s still missing, provide some more technical details for nerds and answer the most commonly asked questions.

So how does it all work?

To avoid scaring the non-technical readers away at the beginning, I’ll start with the basic operating principles and explain where these sounds come from. Every mechanical device with electric motor or any other moving parts makes noise as a side effect. Sometimes that noise can be controlled. and turned into music – which usually involves some level of abuse. All of the devices present in the „orchestra” contain either stepper motors or moving heads (in case of hard drives), which are driven by custom electronic circuits – controllers. Those controllers are connected in a network and can be commanded from the computer to make a specific device (e.g. scanner #2) emit a specific sound (e.g. constant 440hz tone which corresponds to A4 note in music) at a specific point in time. A sequence of those noises and tones makes music – just like with the real instruments. Sounds simple? In principle, yes, but it gets complicated in a larger scale.

How it’s done?

The machine evolved into a relatively large system with multiple custom circuit boards and 3D-printed parts. While making the new Floppotron, one of the main priorities (if not the main) was finishing it in reasonable time. It’s still a hobby project made after hours and not something commercial or mass produced, so you will find some nice solution as well as some janky, quick-and-dirty ones – and that’s the beauty of hobby projects. Let’s get a little more technical. To explain how the system works, I’ll go through the overview first and then will get into details of each individual block. Here’s a simplified schematic od the machine.

To make the old computer hardware play, we need a set of electronic controllers mentioned before but also a proper music (musical sequence) to play. A melody is encoded as a sequence od MIDI events, the same format as all digital synthesizers use. MIDI does not carry any actual audio data, but just short events, like pressing a piano key or twisting a control knob – you can think of it as a digital form of sheet music. Those events are send from the computer to the gateway using USB to MIDI adapter. The gateway is a custom nRF52 microcontroller based device which sits between the PC with MIDI adapter and the network of „instrument” controllers. It receives MIDI data and converts that data to RS-485-based internal protocol which can encapsulate MIDI and some extra stuff. The gateway, protocol and reasoning is described in further section. Those messages are picked by controllers which will turn the digital information into a sound by driving the electric motors or moving