Did you know that the term “bug” was used as far back as Shakespearean times meaning a frightful object (this usage was derived from a Welsh mythological monster called the “Bugbear”)? Furthermore, “bug” was used in Thomas Edison’s time (circa the latter part of the nineteenth century) to imply a glitch, error, or defect in a mechanical system or an industrial process. And what of computing …

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The First Bug
The term bug is now universally accepted by computer users as meaning an error or flaw – either in the machine itself or, perhaps more commonly, in a program (hence the phrase “debugging a program”). The first official record of the use of the word “bug” in the context of computing is associated with the relay-based Harvard Mark II computer, which was in service at the Naval Weapons Center in Dahlgren, Virginia. On September 9th, 1945, a moth flew into one of the relays and jammed it. The offending moth was taped into the logbook alongside the official report, which stated: “First actual case of a bug being found.”

It has now become a popular tradition that it was the legendary Grace Hopper who found the offending insect, but Grace is said to have stated that she wasn’t there when it happened. [An American Naval officer and mathematician, Grace Murray Hopper (1906-1992) was a pioneer in data processing and legend in her own lifetime. Hopper is credited with developing the first compiler (a program that translates a high-level human-readable language into machine code), and was also a supervisor on the project that eventually produced COBOL (Common Business-Oriented Language). In 1983, she became the first woman to achieve the rank of Rear Admiral in the United States Navy.]

It is also widely believed that this incident was the origin of the term “bug,” but this is also not the case. If you read the wording of the report carefully, you can see that the writer is really saying: “Hey, we actually found a bug that was a real bug!”

The Worst Bug
As to the worst computer bug, there are obviously many contenders, some of which are tragic (they cost lives) and some of which are humorous, such as the 1989 case of the court computer in Paris, France, which targeted over 41,000 traffic offenders and issued them with summonses for a variety of crimes, including drug trafficking, extortion, prostitution, and deviant sexual practices. However, there is one bug which certainly caught the popular imagination and which stands proud in the crowd. On 28th July, 1962, the Mariner I space probe was launched from Cape Canaveral on the beginning of its long voyage to Venus. (From 1963 to 1973, Cape Canaveral was known as Cape Kennedy in honor of President John F. Kennedy.)

The flight plan stated that after thirteen minutes a booster engine would accelerate the probe to 25,820 mph; after eighty days the probe’s on-board computer would make any final course corrections; and after one hundred days, Mariner 1 would be in orbit around Venus taking radar pictures of the planet’s surface through its thick cloud cover.

Unfortunately, only four minutes into the flight, Mariner I did an abrupt U-turn and plunged into the Atlantic Ocean. The investigating team found that a logical negation operator had been accidentally omitted from the computer program in charge of controlling the rocket’s engines. On the basis that the launch, including the probe, cost in the region of $10,000,000, this has to rank as one of the more expensive (and visible) bugs in the history of computing. (I bet you’re glad you weren’t that programmer!).

Last but not least, although some references say that Mariner 1 was heading for Mars, its itinerary definitely had Venus penned in at the top of the list (NASA does try to keep track of where they’re attempting to send these things) – trust us on this one, for we have friends at NASA and we know whereof we speak. Mariners 1 and 2 were intended for Venus (only Mariner 2 made it there); Mariners 3 and 4 were aimed at Mars (only Mariner 4 got there); Mariner 5 returned to Venus, Mariners 6, 7, and 9 returned to Mars (Mariner 8 ended up at the bottom of the Atlantic Ocean); and Mariner 10 wended its way to Mercury by way of Venus.

Note: The material presented here was abstracted and condensed from The History of Calculators, Computers, and Other Stuff document provided on the CD-ROM accompanying our book How Computers Do Math (ISBN: 0471732788).