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Drew Breunig Builds an NES CPU Emulator into Qwen3.5-4B’s Weights

1 reports 1 reporting sources 2 hours agoNew

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Drew Breunig built a working Nintendo Entertainment System 6502 CPU emulator into Qwen3.5-4B’s weights, allowing NES ROMs such as Super Mario Bros. to run very slowly inside Qwen, Simon Willison reported. Breunig’s project, nesformer, was inspired by Divyansh Agrawal’s qwenputer. Breunig shared the Opus 5.5 prompts used to build it; according to Willison, Opus apparently found and used NES CPU conformance tests that Christopher Pow released 15 years ago.

Generated by AI from reports · Updated 58 minutes ago

Latest development10/31 05:59 (UTC+8)
Drew Breunig’s nesformer runs an NES CPU emulator inside Qwen3.5-4B weightsSimon Willison

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10/31
  1. Simon Willison
    Drew Breunig’s nesformer runs an NES CPU emulator inside Qwen3.5-4B weights

    Simon Willison reports that Drew Breunig built a working Nintendo Entertainment System 6502 CPU emulator into Qwen3.5-4B’s weights, allowing NES ROMs such as Super Mario Bros to run very slowly inside Qwen. Inspired by Divyansh Agrawal’s qwenputer, Breunig shared the Opus 5.5 prompts used to build it. Opus apparently found and used NES CPU conformance tests released 15 years ago by Christopher Pow.

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