An idealized computing machine consisting of a fixed set of data registers and set of instructions for operating on them. Register machines are also known as counter machines and program machines. Early investigators included Shepherdson and Sturgis (1963) and Minsky (1961). Somewhat similar constructs were also part of Kurt Gödel's 1931 work on representing logic within arithmetic (Wolfram 2002, p. 896).
Wolfram (2002) considers machines with two registers and two operations: "increments" and "decrement-jumps." The above illustration shows 30 steps of a five-instruction program that generate nonrepetitive output (Wolfram 2002, p. 99).
