The car physics, Gold only

2026-10-24, the pod-physics session.

The recorded Gold race (derived/physics/gold-beltane), the ground truth for every physics test since this entry.

The project now works from POD Gold 2.8 alone. The first edition stays as a record of differences in docs/versions.md. Earlier today the port could follow either edition. It now has Gold's constants and layouts only: the brake and torque curve, the longer track faces, the moved track tables and the chassis counter at 0x4f3310.

The tests followed. Until now each function was checked against calls captured on the first edition. Those captures were made again from Gold's own code, running under the emulator on the Gold race: 39 functions, from the vector helpers to the track contact, with 10 to 8,328 calls each. Every call matches the port, byte for byte, except one call that hit the put-back step.

One helper did not come back. In the first edition the track's face tests took the sign of a triple product through a helper of their own. Gold's face tests compute the same thing with dot and cross products, and nothing calls the helper any more, so the port dropped it.

The documents, the step log and the measuring scripts now give Gold's addresses throughout. The labels map (labels/gold/map.tsv) moved most of them. It also showed that Gold split the race block: its first words, the chassis counter among them, now sit apart from the rest.

Next

Putting a car back on the track (0x415730), with the case this race recorded at step 870.