The world's first electronic, digital, programmable computer needs a new home, and you can help by sponsoring one of its valves. If you're using a computer right now, you owe this machine a debt, for a whole bunch of reasons.
Colossus was designed in December of 1944 to help the British crack German communications which had been encrypted using a sophisticated electromechanical machine that the Brits called Tunny. Tunny used a series of 12 rotating wheels to separately encode each character sent in a message, making messages extremely difficult (let's just go ahead and say nearly impossible) to analyze and decrypt.
Tunny might have stayed a mystery except that in 1941, the Germans transmitted a long encrypted message from Athens to Vienna that wasn't received properly, so nearly same message was sent again, using the same encoder wheel settings. This is a major no-no, and with just these two related messages, British mathematicians were eventually able to reconstruct the entire logical structure of the Tunny machine, a staggering achievement.
Even with detailed knowledge of how Tunny worked, it still wasn't possible to efficiently crack coded messages, since the British had no way of knowing what the encoder wheels were set to every day. It was possible to make statistical guesses by testing wheel settings against the encrypted text, but by the time someone could figure out by hand what the settings were, it was usually to late to do anything with the information in the decoded message.
Enter Colossus. Colossus was built in 1943 specifically to analyze encrypted Tunny messages at extremely high speed. The computer was semi-programmable (through switches and plugboards), and with 2,500 vacuum tubes, could make statistical calculations at an effective speed of just under 6 mHz (in 1944!). Colossus didn't have an electronic memory, but instead relied on long strips of paper tape with holes punched in it that would blast through the machine at nearly 50 miles an hour. The computer itself could operate even faster than this, but the tape would start to disintegrate. In normal operation the computer could read 5,000 characters per second off of this tape, returning scores on likely encoder wheel settings and enabling the German codes to be broken in hours instead of weeks and shortening the war by an estimated two years.
"It is regretted that it is not possible to give an adequate idea of the fascination of a Colossus at work; its sheer bulk and apparent complexity; the fantastic speed of thin paper tape round the glittering pulleys; the childish pleasure of not-not, span, print main header and other gadgets; the wizardry of purely mechanical decoding letter by letter (one novice thought she was being hoaxed); the uncanny action of the typewriter in printing the correct scores without and beyond human aid; the stepping of the display; periods of eager expectation culminating in the sudden appearance of the longed-for score; and the strange rhythms characterizing every type of run: the stately break-in, the erratic short run, the regularity of wheel-breaking, the stolid rectangle interrupted by the wild leaps of the carriage-return, the frantic chatter of a motor run, even the ludicrous frenzy of hosts of bogus scores." -General Report on Tunny, 1945
Colossus was extremely secret, of course, and remained so for many years after the end of World War II. The computers themselves were dismantled at the specific directive of Winston Churchill, and the blueprints were burned. It wasn't until the late 70s that details about Colossus began to emerge, and in 1993, some of the original designers got together to rebuild one from scratch. It was operational by 1996, and you can see it running in the video below.
So, here's where you come in: the UK's National Museum of Computing is trying to raise £150,000 for a new gallery in which to display their rebuilt Colossus machine, and they're letting people sponsor individual valves by buying pixels on their website at £10 per block. Remember, in addition to ending World War II several years early, Colossus was the first computer of its kind ever, and to some extent we all owe our technological lives to the revolution that it inspired.