dbreunig/nesformer

Inspired by Divyansh Agrawal's qwenputer, Drew Breunig built a working emulator for the Nintendo Entertainment System 6502 CPU into the weights of Qwen3.5-4B, so NES ROMs such as Super Mario Bros can run inside Qwen, very slowly. In a Hacker News comment he shared the Opus 5.5 prompts he used, which asked the model to explore emulating the chip and RAM with this technique and to build it for fun with weights and a CLI that can be pointed at a ROM. Opus reportedly found and used a collection of NES CPU conformance tests released 15 years ago by Christopher Pow.