The style and sound of older video games is unique enough that they’re still copied in relatively modern games like Undertale, Celeste, or Shovel Knight. There’s also a vibrant chiptune community making music on the older hardware directly. Often this involves hardware modding or otherwise finding chips from older gaming systems to replicate that unique retro gaming sound authentically. But disassembling older systems is not always necessary. Take a look at this Game Boy Advance synthesizer which uses the GBA hardware with no modifications at all.
The key to making this work is the GBA’s multiboot feature, which allowed these systems to send executable code over a link cable to other consoles which didn’t have cartridges. This meant that friends could play multiplayer games without each one needing their own cartridge, but it also means that nowadays people can send their own custom software directly to the console’s RAM without much extra effort. To run the synthesizer software, the GBA is connected to a computer, the software is started, and then when the GBA is powered on the snythesizer is automatically loaded into its RAM. The audio output is played over the headphone jack, and various controls are available on the computer and on the console.
In the video linked below, [Andy] is using the GBA with some other musical hardware and the sounds he’s getting from the unmodified console are impressive. It could certainly be a go-to for anyone interested in getting started in this style of music or who doesn’t want to do something like take apart an original Sega Genesis for the audio circuitry.

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