Colossus was the first computer in the world to be completely electronic, digital and programmable. Designed by Tommy Flowers in the early 1940s and commissioned in 1943, the machine was a special computer focused on cracking Nazi encryption. Colossus did not directly broke the codes directly but instead processed encrypted messages, simulated mechanical codeclocks, and then generated potential key combinations that could be used to decode the encrypted communication.
With modern standards, it was quite limited as far as programmable machines go. It was not possible to store programs in the machine so each new program must be manually entered with a series of power switches and patch cables. When the war was over, it was also of limited scope because it was designed specifically for cryptographic tasks and could not be redirected to serve civilian needs, but since the program was classified until the 1970s there was hardly any worry at the time.
After the program was completed, the majority of documents and drawings were destroyed and for decades, those who worked on the project never got credit for their achievements. During the 2000s, a project began to rebuild the Colossus, using the input and guidance of the remaining engineers who worked on the original computer. The project was completed in 2007 and the rebuilt Colossus competed in a Cipher Challenge competition to see what codeclocks around the world could decipher original WWII encrypted messages the fastest. The machine did not win (it lost to a modern computer), but in the process it was discovered that the simple purpose of Colossus was about a 5.8 MHz chip – an extremely impressive view for a computer built in the early 1940s.
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