Source time Edition date
IndustrySimon Willison
dbreunig/nesformer
Worth reading to see how Simon Willison surfaces dbreunig/nesformer, a small hands-on demo that shows what building with a transformer actually costs in effort and clarity.
Judgment
Drew Breunig’s 'just for fun' build sets the decision for other builders: whether to embed an NES 6502 CPU in Qwen3.5-4B weights for a self-contained ROM-running CLI, accepting very slow Super Mario Bros rather than using a conventional emulator.
Basis
Simon Willison reports that Drew Breunig, inspired by Divyansh Agrawal’s qwenputer, baked a working NES 6502 CPU emulator into the weights of Qwen3.5-4B; Willison says you can play NES ROMs such as Super Mario Bros, very slowly, inside Qwen. In a Hacker News comment, Breunig reveals the Opus 5.5 prompts: read the qwenputer article and relevant source, explore emulating the NES chip and RAM with the technique, ask what model size would be needed and whether smaller/faster models could hit standard clockspeed, then say 'I think we should build it! Just for fun. It's okay if it's not fast' and aim for weights plus a CLI pointed at a ROM. Willison adds that Opus apparently found and used Christopher Pow’s NES CPU conformance tests, released 15 years ago. Mechanism: model weights encode CPU/RAM behavior; a CLI runs ROMs; conformance tests check the emulated CPU.
- Read qwenputerprompt
- Explore CPU/RAMsize?
- Model size/speedbuild
- Build weights+CLIvalidate
- Pow conformance
Unclear The source does not report the achieved clock speed, how many Pow conformance tests pass, or which NES ROMs run beyond the Super Mario Bros example.
Next Check the nesformer repository or demo for a runnable CLI command and any reported Pow conformance-test pass count.