NES 6502 emulator encoded in Qwen3.5-4B weights
Original title: dbreunig/nesformer
Drew Breunig’s nesformer can run Super Mario Bros inside Qwen, very slowly, using a method inspired by qwenputer.
Simon Willison reports that Drew Breunig encoded a working Nintendo Entertainment System 6502 emulator into the weights of Qwen3.5-4B. The project, nesformer, was inspired by Divyansh Agrawal’s qwenputer. On Hacker News, Breunig shared Opus 5.5 prompts he used to explore emulating the chip and RAM. The snippet ends before any stated conclusion on required model size.
Unconfirmed: The feed cuts off before any claim about the model size needed.
- The demo runs NES ROMs, including Super Mario Bros, inside the model.
- It emulates an NES 6502 CPU rather than releasing a new base model.
- Breunig said he used Opus 5.5 prompts while building the system.
- AI models
- Qwen3.5-4BOpus 5.5
From the original article
dbreunig/nesformer Inspired by qwenputer by Divyansh Agrawal, Drew Breunig baked a working emulator for a Nintendo Entertainment System 6502 CPU into the weights of Qwen3. 5-4B. You can now play NES ROMs such as Super Mario Bros (very slowly) running inside Qwen!
simonwillison.net
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