Wireworld is a 4-state totalistic cellular automaton operating in 2D Moore neighborhood first proposed by Brian Silverman in 1987. It became widely known after being described in Scientific American in 1990. Wireworld is particularly suited for simulating digital electronic circuits. Given an infinite tiling of properly put "wires", Wireworld is Turing-complete.
Unlike Life-like cellular automata, the entire evolution of Wireworld patterns is confined within so-called wires, static structures, which may not be created, modified or destroyed, but may change the state of their cells in a way resembling the behavior of electronic circuits. Oscillators in Wireworld are wire structures that pass "electrons" periodically, while clocks, electron-producing circuits, may be considered an analogue of guns.
The Wireworld universe has the following states:
- empty (black),
- electron head (blue),
- electron tail (red),
- conductor (yellow).
Cells behave as follows:
- empty → empty,
- electron head → electron tail,
- electron tail → conductor,
- conductor → electron head if exactly one or two of the neighboring cells are electron heads, otherwise remains conductor.
Wireworld rules allow to construct very small and robust logic gates, triggers, memory banks etc., from which complex computational devices could be easily built.
In September 2004 David Moore and Mark Owen released a Wireworld computer, in which the results of calculations are shown in seven-segment displays by running "electrons". The computer's instruction set is a highly orthogonal RISC architecture. The program, CPU status and data are stored in a bank of 64 16-bit registers. According to the authors, the computer was designed, with the help of many others, between 1990 and 1992. The version of it included in Golly is preprogrammed to compute and display the sequence of prime numbers.