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Turing machine
1936
The abstract machine Alan Turing described in 1936, a tape-and-head model that formally defines what is computable.
Turing machine Online Emulator
Play Turing machine using JavaScript directly in your browser.
Controls
Loads the 3-state busy-beaver champion by default: it runs on its own, writes six 1s and halts after 14 steps. Open the debugger (or add ?debug) to pause, single-step one transition at a time, set a breakpoint on entering a state, or watch a tape index. The on-screen panel switches machine (BB-3 / BB-4 / binary increment), writes the cell under the head, and moves the head. Keys: 0/1 write, ← → move the head, Space steps, R resets.
Loads the 3-state busy-beaver champion by default: it runs on its own, writes six 1s and halts after 14 steps. Open the debugger (or add ?debug) to pause, single-step one transition at a time, set a breakpoint on entering a state, or watch a tape index. The on-screen panel switches machine (BB-3 / BB-4 / binary increment), writes the cell under the head, and moves the head. Keys: 0/1 write, ← → move the head, Space steps, R resets.
Loads the 3-state busy-beaver champion by default: it runs on its own, writes six 1s and halts after 14 steps. Open the debugger (or add ?debug) to pause, single-step one transition at a time, set a breakpoint on entering a state, or watch a tape index. The on-screen panel switches machine (BB-3 / BB-4 / binary increment), writes the cell under the head, and moves the head. Keys: 0/1 write, ← → move the head, Space steps, R resets.
Configurations
| Configuration | Emulator | Machine | OS | Legal | |
|---|---|---|---|---|---|
| 3-state Busy Beaver | Turing machine simulator | Turing machine | open | Open ⛶ | |
| 4-state Busy Beaver | Turing machine simulator | Turing machine | open | Open ⛶ | |
| Binary increment | Turing machine simulator | Turing machine | open | Open ⛶ |
Machines
Emulators
| Emulator | Type | License | Site |
|---|---|---|---|
| Morphett Turing Machine Simulator | online | Freeware | Website ↗ |
| Turing Machine Simulator | online | Freeware | Website ↗ |
| Turing machine simulator | online | Public domain | Website ↗ |
| turingmachine.io | online | MIT | Website ↗ |
Reference & documentation
External technical references for programming Turing machine and for writing emulators.
| Resource | Type | Notes |
|---|---|---|
| BB(5) champion machine - BusyBeaverWiki ↗ | Format | Standard compact TM text notation (1RB1LC_...) |
| Neary & Woods, Four Small Universal Turing Machines ↗ | Instruction set | Explicit minimal universal transition tables to implement |
| Universal Turing machine (Wikipedia) ↗ | Instruction set | Turing's action table and symbol encoding scheme |
| Morphett simulator - tuple language reference ↗ | Programming | state symbol write direction newstate; documented tuple syntax |
| Turing, On Computable Numbers (1936, full text) ↗ | Reference | Original paper defining the machine and its tables |
| Turing Machines (Stanford Encyclopedia of Philosophy) ↗ | Reference | Rigorous formal quadruple and transition-function definition |
| milosz08/turing-machine-simulator (source) ↗ | Source | Deterministic simulator with custom ASM compiler, TypeScript |
| The Busy Beaver Challenge - method & machine database ↗ | Test suite | 88M-machine database plus halting deciders to conform against |
| turingmachine.io interactive visualizer ↗ | Tool | YAML-specified machines with animated tape execution |
| Morphett Turing machine simulator ↗ | Tool | Browser simulator with step, breakpoints, example programs |