Colossus

The British codebreaking computer of Bletchley Park, which attacked the Lorenz cipher and helped shorten the war.

Core Principles & Analysis

• Tommy Flowers built the first Colossus in 1943–44; ten stood by VE Day.
• It read paper tape at 5,000 characters per second — faster than anything before it.
• Kept secret into the 1970s, its existence rewrote the history of computing when revealed.