The Turing Machine, a theoretical computer, never actually existed. But Turing argued a computing machine with the power to read symbols on an infinitely long tape and to manipulate them and add its own would, in effect, be thinking.
Google's Turing Machine doodle asks computer users to change a binary number into the company name, PC World reported.
Turing led the British team that cracked the German Enigma code during World War II. He took his own life in 1954, two years after his arrest for homosexuality, supposedly eating a cyanide-coated apple, a method copied from the Walt Disney movie "Snow White."
Turing's test for thinking was whether a machine conversing with a human by computer could convince someone it was also human. Robert Epstein, a psychologist and former editor in chief of Psychology Today, reported that in 2006 he carried on a four-month flirtation online with a Russian woman named Ivana before he figured out she was actually a bot, a software program designed to deceive people on matchmaking Web sites, The Christian Science Monitor reported.