An operating system built out of a Turing machine's parts. The tape is a byte array, the head is an Intel 8080's program counter, and the finite control is a six-state kernel. One C99 core runs it as a native binary and, compiled to WebAssembly, in this page.
The live machine needs JavaScript and WebAssembly. The source and the documentation do not: github.com/jgoetzmann/Turing-Machine-OS.