# Elementary Automata — Randomly

> All 256 rules, including the one that is a PRNG. One of 63 generators at [Randomly](https://randomly.cluxnei.dev), a library of random generators seeded from verifiable real-world entropy. Free HTTP API, no key, no signup.

## `patterns.automaton` — Elementary Automata

All 256 rules, including the one that is a PRNG.

| | |
|---|---|
| **Key** | `patterns.automaton` |
| **Module** | `patterns` |
| **Version** | `1` — a permalink carries this, and a replay against a different version returns `409` rather than something else |
| **Formats** | `application/json`, `text/plain`, `image/png` |
| **Studio** | https://randomly.cluxnei.dev/g/patterns/automaton |
| **API** | `GET https://randomly.cluxnei.dev/api/v1/g/patterns.automaton` |

`value` is a **render spec** — algorithm, parameters, palette and a render key — not pixels. Ask for `format=png` to get the image.

| Parameter | Type | Default | Accepts | What it does |
|---|---|---|---|---|
| `width` | int | `900` | `200` – `2048` | Width |
| `height` | int | `600` | `200` – `2048` | Height |
| `preset` | enum | `r30` | `custom`, `r30`, `r110`, `r90`, `r150`, `r184` | Rule |
| `rule` | int | `30` | `0` – `255` | Rule number — Every rule is one byte: bit i is what the neighbourhood with binary value i becomes. Only used when the preset is Custom. |
| `start` | enum | `centre` | `centre`, `random` | First row — One cell shows the rule's own geometry; a random row shows what it does to noise. |
| `density` | float | `0.5` | `0.02` – `0.98` | Start density — Only used by the random first row. |
| `cell` | int | `3` | `1` – `16` | Cell size — Pixels per cell. Smaller means more generations on screen. |
| `wrap` | bool | `true` | `true`, `false` | Wrap edges — Off, the world has walls and the pattern reflects off them. |
| `palette` | enum | `mono` | `golden`, `analogous`, `complementary`, `triadic`, `split`, `viridis`, `magma`, `mono` | Colour |

Out-of-range numbers are **clamped, not rejected**, so a request never fails for being
ambitious — but it may not do what you meant. Unknown keys are dropped and missing ones
fall back to the defaults above.

```bash
curl -s 'https://randomly.cluxnei.dev/api/v1/g/patterns.automaton?width=900&height=600&preset=r30' -H 'Accept: text/plain'
curl -o out.png 'https://randomly.cluxnei.dev/api/v1/g/patterns.automaton?width=900&height=600&preset=r30&format=png'
```

## The receipt

Every result carries one, naming the physical source of the randomness and linking to the
third party's own record of it:

```json
"receipt": {
  "source": "seismic",
  "source_label": "USGS Seismic Feed",
  "class": "C",
  "caveat": "Carries only tens of bits of genuine surprise. Always mixed with the OS CSPRNG.",
  "narrative": "A magnitude 3.6 earthquake, 67 km N of Culebra, Puerto Rico, 39.6 km down — 52 minutes ago.",
  "proof_url": "https://earthquake.usgs.gov/earthquakes/eventpage/us7000th33",
  "mixed_with_csprng": true,
  "degraded": false
}
```

Pick the source with `?source=`, or leave it at the default `auto`:

- **Class A** (Cryptographic) — `csprng`, `anu-qrng`, `random-org`
- **Class B** (Public beacon) — `nist-beacon`, `drand`, `bitcoin`. Published openly — anyone can look this value up after the fact.
- **Class C** (Observational) — `seismic`, `space-weather`, `atmosphere`, `iss`. Carries only tens of bits of genuine surprise. Always mixed with the OS CSPRNG.

## More

- [The full API contract](https://randomly.cluxnei.dev/api.md)
- [Everything in one file](https://randomly.cluxnei.dev/llms-full.txt)
- [The catalogue as JSON](https://randomly.cluxnei.dev/api/v1/generators)
- [This generator in the browser](https://randomly.cluxnei.dev/g/patterns/automaton)