1st actual computer bug found, September 9, 1947

In 1947, a team of engineers working on the Mark II Aiken Relay Calculator at Harvard University had a problem in one of the circuits of the long glass-enclosed computer. A member of the programming team, Grace Hopper, recorded the story in her log book:  “It was over in another building, and the windows had no screens on them and we were working on it at night, of course, and all the bugs in the world came in. And one night she (Mark II) conked out and we went to look for the bug and found an actual large moth, about four inches in wing span, in one of the relays beaten to death, and we took it out and put it in the log book and pasted Scotch tape over it.”

According to Hopper, from then on, when anything went wrong with a computer, they said it had bugs in it. The term “bug” had been used by engineers to describe flaws in machines, but Hopper popularized “bug” and “debug” as early computer-programmer language. She was an originator of electronic computer automatic programming and a computer pioneer while working for the Navy, where she was a Rear Admiral. As a lecturer, she often told the story of the computer bug. The Mark II was an electromechanical computer built at Harvard and financed by the US Navy.