The Origin of the first Computer "Bug"

Gordonator SG

The First Computer Bug

In 1945, Naval officer and mathematician Grace Murray Hopper was working on the Harvard University Mark II Aiken Relay Calculator (a primitive computer) which was in service at the Naval Weapons Center in Dahlgren, Virginia.

On the 9th of September, 1945, when the machine was experiencing problems, an investigation showed that there was a moth which flew into one of the relays and jammed it.

The offending moth was taped into the log book alongside the official report, which stated: "First actual case of a bug being found."

The moth been taped onto the logbook. Click the picture to see a larger version.

The word went out that they had "debugged" the machine and the term "debugging a computer program" was born.

It has now become a popular tradition that it was the legendary American Naval officer and mathematician Grace Murray Hopper who found the offending insect, but it's also said that she wasn't there when it happened.

Grace Murray Hopper orking on a early computer

Grace was a pioneer in data processing and is credited with developing the first compiler, which is a program that translates a high-level human-readable language into the machine language understood by the computer. In 1983, Grace became the first woman to achieve the rank of rear admiral in the United States Navy.

The logbook, with the moth still taped by the entry, is on display in the History of American Technology Museum.

Gordonator SG

where did the term "bug" come from?

Well, the entry ("First actual case of bug being found." ) shows that the term bug was already in use before the moth was discovered. Grace Hopper also reported that the term "bug" was used to describe problems in radar electronics during WWII.

The term was use during Thomas Edison's life to mean an industrial defect. And in Hawkin's New Catechism of Electricity, an 1896 electrical handbook from Theo. Audel & Co.) included the entry:

The term "bug" is used to a limited extent to designate any fault or trouble in the connections or working of electric apparatus.

In discussing the origin of the term, the book notes that the term is:

said to have originated in quadruplex telegraphy and have been transferred to all electric apparatus.

Common folk etymology says that the phrase "bugs in a telephone cable" was used to account for noisy lines. There is no support for this derivation.

However, the term "bug" was used in the early days of telegraphy. There were the older "manual" keyers that required the operator to code the dots and dashes. And there were the newer, semi-automatic keyers that would send a string of dots automatically. These semi-automatic keyers were called "bugs". One of the most common brands of these keyers, the Vibroplex, used (and still does use) a graphic of a beetle.

These semi-automatic "bugs" were very useful, but required both skill and experience to use. If you were not experienced, using such a "bug" would mean garbled Morse Code.

Radio technicians also used the term "bug" to describe a roach-shaped device consisting of a coil of wire with the two ends of wire sticking out and bent back to nearly touch each other. This device was used to look for radio emissions. This term "bug" was probably a predecessor to the modern use of "bug" to mean a covert monitoring or listening device.

But, lets go way, way back to Shakespeare. In Henry VI, part III, Act V, Scene II, King Edward says "So, lie thout there. Die though; and die our fear; For Warwick was a bug that fear'd us all."

Samuel Johnson's first dictionary includes a definition of "bug" to mean:

a fightful object; a walking spectre