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47 lines
1.9 KiB
Markdown
47 lines
1.9 KiB
Markdown
# Real VT1200 boot recording — reference material
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Source: `video/DEC VT1200 Hardware X11 terminal boot and demo. [j_mJB3asDgE].mkv`
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(201 MB, **gitignored** — it is a YouTube download and trivially re-obtainable).
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Everything committed here is **derived** from it: contact sheets for navigation,
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full-resolution frames for detail.
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## Regenerating
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```sh
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V="video/DEC VT1200 Hardware X11 terminal boot and demo. [j_mJB3asDgE].mkv"
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# contact sheets: one frame per 2 s, 6x6 tiles
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ffmpeg -v error -y -i "$V" -vf "fps=1/2,scale=320:-1,tile=6x6" sheet_%02d.png
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# full-resolution frame at a chosen time — OUTPUT seek; input seek (-ss before -i)
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# fails on this filename with "Invalid argument"
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ffmpeg -v error -y -i "$V" -ss 26 -frames:v 1 real_t26.png
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```
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## The real boot timeline
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This is the ground truth the harness is compared against.
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| video time | what is on screen |
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|---|---|
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| 0:00–0:12 | **nothing** — the monitor's own blue no-signal backdrop |
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| ~0:13 | the terminal starts driving the display |
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| 0:14–0:44 | the self-test **pie / progress disc** sweeping to completion |
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| ~0:45 | wipe to black |
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| ~0:48 | a **dialog box** (the Terminal Manager) |
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| ~1:08 | a light (mostly white) screen |
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The harness reaches the X11 weave and the Terminal Manager via
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`VT1200_SKIP_LEVEL1=1`; on real hardware level 1 passes, so it goes further.
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## One correction kept deliberately
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The low-resolution contact sheets *appeared* to show a **text block** at ~0:14, and
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that was briefly reported as a real screen. A full-resolution crop
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(`real_text_crop.png`, taken at 0:14.2) shows the screen is **blank blue** — the
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monitor's no-signal state. The "text" was a scaling/compression artefact of a
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320-pixel tile.
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**A contact sheet tells you *when* something happens, not *what* it says.** Crop and
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up-scale before reading anything off one — the same class of mistake as concluding
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"it never paints" from a single frame.
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