Issue No. 08 - August (1975 vol. 24)
F. Noural , Department of Computer and Statistics, University of Ferdowsi
The design and development of a universal computer in a four-state, five-neighbor cellular model is presented. The underlying structure of the model is an infinite two-dimensional space divided into unit cells each of which can be in one of four states 0, 1, 2, and x. State 0 is the quiescent state, states 1 and 2 are mainly used for signaling, while state x is used for structure purposes. Cells change states at discrete times according to a transition rule which determines the next state of a cell as a function of the present state of the cell itself and its four nondiagonal adjacent neighbors. A configuration is defined to be an assignment of states to all cells in the space such that only a finite number of cells are in the nonquiescent states. A set of configurations, called primitive elements, consisting of the wire, the junction, the corner, the delay, the extendible wire, and the crossover are introduced. Using these elements, a functionally complete set of configurations, called basic organs, comprised of the diode, the OR, the EXCLUSIVE-OR, the clock, and the NOT are developed. The primitive elements and the basic organs are utilized to design four general-purpose components?the encoder, the decoder, the recognizer, and the pulser. These components are used primarily for the detection and the generation of command instructions to and from the universal computer.
Cellular automata, finite-state automata, Minsky's 2-register machine, universal computer.
R. Kashef and F. Noural, "A Universal Four-State Cellular Computer," in IEEE Transactions on Computers, vol. 24, no. , pp. 766-776, 1975.