Google has posted a look back at Colossus, the world’s first programmable electronic computer. Created by Tommy Flowers at the Bletchley Park decryption center in England, it was designed to intercept and interpret coded messages sent by German machines during World War II. Bletchley Park was where the Enigma codes were finally broken, but by 1943 the Germans were using a new and more complex system called Lorenz. With its messages taking up to eight weeks to decipher by hand and the codes changing every night, Flowers decided that the only way to break Lorenz quickly enough would be to develop a new electronic computer system.
The machine used around 1,600 thermionic glass valves, sparking fear of unreliability, but Flowers managed to convince his superiors that it would be safe as long as it was never switched off. After several months of work the first Colossus went into action in January 1944, and it was such a success that around ten were eventually produced, including a faster Mark II variant with 2,400 valves. The computer allowed the British codebreakers to read messages almost as quickly as the German recipients, including in some cases Adolf Hitler himself. Prime Minister Sir Winston Churchill believed that Colossus’s breaking of the German High Command code ultimately shortened the war by two years. For security reasons, all but two of the machines were destroyed at the end of the war, with mention of the project forbidden under the Official Secrets Act.