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Computer bug: it all started with an actual insect

The term “computer bug” is very common, but have you thought about the history behind it? As it turns out, there was an actual insect involved! I have mentioned this story briefly in my post about Grace Hopper, an incredible woman who has revolutionised the way we write code, but I wanted to dedicate a separate post to it – as it is pretty entertaining.

The first computer bug

The first computer bug


During World War II, the US allocated a lot of its resources towards the development of computers, giant calculators that were used to optimise trajectories of missiles and carry out other types of calculations. We are in 1947, the war is just over, but research and development continue. A group of scientists at Harvard were working on Mark II, an electromechanical computer and a faster version of Mark I.

On September 9th the computer was suffering a failure. After an inspection, a moth was found – it was jamming the mechanisms. Grace Hopper recorded the incident in the logbook, describing it as the “First actual case of bug being found”. Not only this phrase shows her sense of humour, but also the fact that the word “bug” has been used before.

According to a source, the term “bug” has in fact been used by engineers long before computers. Oxford English Dictionary uses a quote from Pall Mall Gazette of 11 March 1889 in order to explain what ‘discovering a bug’ meant at the time: “an expression for solving a difficulty, and implying that some imaginary insect has secreted itself inside and is causing all the trouble”. At the time the word was another word for malfunctioning of telegraphs and other 19-century machinery.

So the insect that caused these glitches was always imaginary. When Grace Hopper’s team found an actual one, the notion became more real and the term was popularized among a wider audience:

“From then on, when anything went wrong with a computer, we said it had bugs in it.”

Grace Hopper

As you can see, even though the concept already existed before there was an actual bug involved, the moth helped to popularise it. Grace Hopper gave it a “push” that it needed to become as widely used as it is now.

I love finding these sort of stories and couldn’t have not shared it with you. I hope you’ve enjoyed it!

<the blonde>

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