On 29 October 1969, two scientists established a connection between computers some 350 miles away and started typing a message. Halfway through, it crashed. They sat down with the BBC 55 years later.
At the height of the Cold War, Charley Kline and Bill Duvall were two bright-eyed engineers on the front lines of one of technology's most ambitious experiments. Kline, a 21-year-old graduate student at the University of California, Los Angeles (UCLA), and Duvall, a 29-year-old systems programmer at Stanford Research Institute (SRI), were working on a system called Arpanet, short for the Advanced Research Projects Agency Network. Funded by the US Department of Defense, the project aimed to create a network that could directly share data without relying on telephone lines. Instead, this system used a method of data delivery called "packet switching" that would later form the basis for the modern internet.
It was the first test of a technology that would change almost every facet of human life. But before it could work, you had to log in.