The Google doole spell out the word Google in binary.
From The Guardian:
Interactive version of computing device celebrates 100th anniversary of birth of Enigma codebreaker.
A functioning Turing machine, a representation of a computing device, is the latest Google doodle, which celebrates the birth of Alan Turing on 23 June, 1912.
A Turing machine is a device that manipulates symbols on a strip of tape according to a table of rules and was developed by the scientist in 1936.
Turing, the father of computing and artificial intelligence, is best known for his contribution to cracking the German Enigma secret codes with the creation of early computers such as the bombe.
The cracking of the code allowed the Allies to track German military and naval units and destroy them.
Before the war started, Turing had already made an impact on the theory that would pave the way for the construction of the first computers. In 1938 he received his PhD from Princeton in the US.
After the war, Turing worked at the National Physical Laboratory and the University of Manchester.
In 1942, Turing was found guilty of homosexuality. He agreed to be chemically castrated which entailed being given female hormones. Two years later he killed himself at the age of 41.
In 2009, the British prime minister, Gordon Brown, officially apologised for Turing’s treatment, although he was not given a posthumous pardon.