Historians think Colossus shortened the war and saved many lives.
Britain's spy agency, GCHQ, has released never before seen images of Colossus, the UK's secret code-breaking computer credited with helping the Allies win World War Two. The agency is publishing them to mark the 80th anniversary of the device's invention. It says they "shed new light" on the "genesis and workings of Colossus", which is acclaimed as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program. Alan Turing's use of probability in cryptanalysis contributed to its design.
Anne Keast-Butler, director of GCHQ, said the pictures were a reminder of the "creativity and ingenuity" required to keep the country safe. "Technological innovation has always been at the centre of our work here at GCHQ, and Colossus is a perfect example of how our staff keep us at the forefront of new technology - even when we can't talk about it", she said.
Perhaps remarkably, Colossus wasn't formally acknowledged by the UK intelligence services until the 2000's.
The first Colossus began operating from Bletchley Park, the home of the UK's codebreakers, in early 1944. By the end of the war there were 10 computers helping to decipher the Nazi messages.
Fitted with 2,500 valves and standing at more than 2 metres tall, Colossus required a team of skilled operators and technicians to run and maintain it. Often they were members of the Women's Royal Naval Service (Wrens) - one of the new images shows Wrens working on the machine.
By the end of the war, 63 million characters of high grade German messages had been decrypted by the 550 people working on the computers. One of its notable successes was helping the Allies know that Hitler had swallowed the bait that the D-Day landings in June 1944 would be at Calais rather than Normandy.
Today's Articles
What Went Right Last Week: Synopsis of the most important good news from around the world.
Vinted Minted: The woman who sold her clothes to clear out her closet and created a billion dollar empire.
World's Weirdest Winter Sports: For some, classic winter sports like skiing are a great way to experience an adrenaline rush in nature. For others, it's simply not enough!
Hilarious Tweets: Funny musings on parenting, marriage, Christmas, and children mispronouncing words.
Snap Happy: Cheeky pets caught photobombing.
Top Performers: Last week's most popular (and amusing) articles, plus the most watched mood boosting video.