  In 1936, at Cambridge University, Turing invented the principle of the modern computer. He described an abstract digital computing machine consisting of a limitless memory and a scanner that moves back and forth through the memory, symbol by symbol, reading what it finds and writing further symbols (Turing [1936]). The actions of the scanner are dictated by a program of instructions that is stored in the memory in the form of symbols. This is Turing's stored-program concept, and implicit in it is the possibility of the machine operating on and modifying its own program. (In London in 1947, in the course of what was, so far as is known, the earliest public lecture to mention computer intelligence, Turing said, ‘What we want is a machine that can learn from experience’, adding that the ‘possibility of letting the machine alter its own instructions provides the mechanism for this’ (Turing [1947] p. 393). Turing's computing machine of 1936 is now known simply as the universal Turing machine. Cambridge mathematician Max Newman remarked that right from the start Turing was interested in the possibility of actually building a computing machine of the sort that he had described (Newman in interview with Christopher Evans in Evans [197?]. 