5d72bda77d
The time-based-clock claim rests on two captures that happened to run at different speeds. Nobody has changed the frame rate on purpose and watched. --framerate_limit=30 halves Xenia's vblank ceiling. Predictions committed before the run: quantity frame-based time-based (my claim) presents/s ~27 ~27 modal alpha step 17, unchanged 34, DOUBLED units/s ~30, halved ~60, unchanged splash dwells ~8.5 / ~7.0 s ~4.2 / ~3.5 s, unchanged Accept time-based only if the step lands in 30-38 AND the dwell stays within 10% of 4.2/3.5 s. If the step stays 17 and the dwell doubles, the claim is refuted, the clock is frame-based, and the port's 60 is unsupported again. The control is the present rate itself, read FIRST: a doubled step also appears if the limiter did nothing, so if presents/s does not fall to ~27 neither prediction is tested. Second control: the eight splash quad rects must be unchanged, or something other than the frame rate differs between runs. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Jc4pciRArGHfxGGhEbwp5t
67 lines
2.8 KiB
Markdown
67 lines
2.8 KiB
Markdown
# Pre-registration — force the frame rate, and see which quantity moves
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**Committed BEFORE the capture.** 2026-09-01. The designed falsification of
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[`units-per-frame-is-not-a-constant.md`](units-per-frame-is-not-a-constant.md),
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which currently rests on two captures that happened to run at different speeds
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rather than on one made to.
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---
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## The claim under test
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> The UI clock advances by **elapsed time**, not by frame count. `units/present`
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> is an artefact of the presentation rate; **`units/second ≈ 60` is the
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> invariant.**
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Evidence so far, all opportunistic:
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| capture | presents/s | modal Δα | ⇒ units/present | ⇒ units/s |
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|---|---|---|---|---|
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| `h3` | 27.2 | **34** | 2.0 | 54.4 |
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| boot 1 | 51.4 | **17** | 1.0 | 51.4 |
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| boot 2 | 54.8 | **17** | 1.0 | 61.3 / 60.3 (from dwell) |
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Two of the three ran at nearly the same rate. **Nobody has yet changed the frame
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rate on purpose and watched.**
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## The experiment
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`--framerate_limit=30`. Xenia's limiter (`graphics_system.cc`) then marks vblank
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at 30 Hz instead of 60, halving the ceiling on presents.
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## 🔴 The predictions, stated now
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| quantity | frame-based clock | **time-based clock (my claim)** |
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|---|---|---|
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| presents/s | ~27 | ~27 |
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| **modal Δα per present** | **17, unchanged** | **34, doubled** |
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| **units/s** | **~30, halved** | **~60, unchanged** |
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| publisher splash dwell | ~8.5 s, doubled | **~4.2 s, unchanged** |
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| developer splash dwell | ~7.0 s | **~3.5 s, unchanged** |
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**These diverge on every row but the first.** I accept the time-based reading only
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if the modal step lands in **30–38** *and* the dwell stays within 10 % of 4.2 /
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3.5 s. If the step stays at 17 and the dwell doubles, **my claim is refuted and
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`units/s` is 30 at this limit**, which would mean the clock is frame-based after
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all and the whole rate question reopens with the port's 60 unsupported again.
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⚠️ Note which way the risk runs: a doubled step is the result that *confirms* me,
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and it is also what a frame-based clock would show if the limiter did not actually
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take effect. **So the control is the present rate itself** — if presents/s does
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not fall to ~27, the flag did nothing and neither prediction is tested. That is
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the first number I will read, before the step.
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## Second control
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The splash **quad geometry** must be unchanged — same eight NDC rects. If the
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rects move, something other than the frame rate changed between runs and the
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comparison is not clean.
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## What this cannot settle
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Whether the console's rate is 60. Everything here is measured under Canary's
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limiter; the claim being tested is only that the clock is *time*-driven and that
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its rate is ~60 units/s **as this emulator runs it**. A time-based clock is
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immune to dropped frames, which is why that is worth something — but it is not
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the console.
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