Drew Breunig’s Nesformer compiles a Nintendo Entertainment System processor into a Qwen3.5 model architecture. A compiler calculates the weights instead of learning them from data. The model generates processor execution traces while host software handles graphics and controllers. The project runs selected games, with substantial speed and compatibility limits.
Drew Breunig released Nesformer, an open-source project that places a Nintendo Entertainment System processor in a Qwen3.5 model architecture. A compiler calculates the weights rather than learning them through training. The model generates the processor’s execution trace one token at a time. Simon Willison’s account identifies the same project and its ability to run selected console games, describing execution as very slow.[1], [2]
Inside the model are the processor core, working memory and cartridge program data. Host software draws the picture and handles controller input around that core. Audio is absent. The project builds on Divyansh Agrawal’s Qwenputer compiler work. It supports a particular cartridge layout; games requiring bank-switching hardware fall outside the implementation. The weights represent a specific processor circuit and its state, while parts of the console remain in the host program.[1]
Breunig documents checks against a reference processor emulator and processor conformance tests. For the bundled test games, the project reports matching execution traces and rendered frames. Those comparisons concern the supplied tests and supported behavior. The developer also reports that Nesformer runs roughly 150 to 290 times slower than the real console. The implementation supports official processor instructions and has further limits involving interrupts and graphics behavior, set out in the repository documentation.[1]
