A Game Boy Advance can run as a fully functional synthesizer with zero hardware modification. The project, documented at computer.musicthing.co.uk, exploits the GBA's built-in multiboot feature: a link cable delivers executable code directly into the console's RAM, bypassing the cartridge slot entirely. Audio comes out the headphone jack. No soldering, no chip harvesting, no disassembly.
The multiboot protocol was designed for cartridge-free multiplayer, letting one GBA broadcast game code to others over a link cable. That same pathway now loads custom synth software at boot. The GBA becomes a CV-controlled Eurorack voice, demonstrated by Andy in a video showing it integrated with external modular hardware, producing tones that hold up against purpose-built chiptune rigs.
The deeper story here is not the sound. It is the method. Understanding how multiboot works, what the GBA's audio hardware is actually capable of, and how Andy routed CV control into a stock consumer device is worth reading in full. This approach sidesteps the increasingly scarce and fragile original chips that projects like the Sega Genesis audio harvests depend on.
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