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Thursday, December 4, 2014

She discovered the first computer 'bug'

by Mark A. Ollig

In 1947, computer programmer Grace Murray Hopper was tracing out a problem in the Navy’s Mark II Aiken electromechanical computer.

The source of the problem turned out to be a moth, which had become trapped in a mechanical electromagnetic relay, thus preventing current flow.

Having worked with mechanical relays many years ago, my guess is the moth was probably stuck between the relay’s switch contacts, or between the metal pivot armature and the electromagnet coil.

Hopper removed the moth from the relay and recorded the event in her daily log book, writing: “Relay #70 Panel F (moth) in relay.”

She even taped the cause of the trouble; the said moth, onto the page in the daily log book.

Under the moth, Hopper wrote: “First actual case of bug being found.”

I can imagine the smile on her face when she wrote that sentence.

And so, for the last 67 years, whenever a problem is encountered with a computer program, we commonly say there is a bug in it – due to Grace Murray Hopper.

This humble, entomologist-aware columnist wondered if a moth should be called an insect instead of a bug.

Surprisingly, I found there is much discussion and chatter on the Internet regarding the distinction between bugs and insects.

One highly-regarded encyclopedia states moths are related to butterflies, and thus belong to the order of Lepidoptera, which are nocturnal flying insects.

I read bugs belong to an order called Hemiptera, and insects belong to a class called Insecta.

Attempting to delve into more detail with these descriptions is starting to bug me; it also forces me, at this time, to plead ignorant.

In 1944, Grace Hopper was one of the first programmers of the new IBM automatic sequence controlled calculator, or electromechanical computer called the Harvard Mark I.

This computer was used at Harvard University.

I noticed the “Mark” in the computer name, but it was a man named Howard Aiken, a Harvard University graduate student, who created the original plans for this huge, large-scale, automatic computing machine.

The Harvard Mark I computer cabinet bay was 8 feet high, 51 feet long, and 3 feet deep.

It weighed 5 tons, included 765,000 parts, 530 miles of wire, 3,500 multiple relays, 2,225 numeral counter units, and 1,484 10-pole switches; meaning, each switch could control 10 circuits at one time.

Four paper-tape readers and a series of hole-punched paper tape were used for the input, while the output functions used two IBM electric typewriters for printouts, and a series of punched cards.

“It had 72 words of storage and could perform three additions a second,” Hopper reportedly said about the Harvard Mark I computer.

The Mark I was shipped to Harvard University in 1944.

IBM’s cost for the Mark I was $200,000. They also added $100,000 to cover the computer’s operating expenses.

The Harvard Mark I computer is said to have been in continuous operation during 1944 and 1945.

It was solving wartime ballistic calculation problems during the course of World War II, while it was housed in the basement of the Cruft Laboratory at Harvard University.

One of the problems the computer worked included determining the correct set of calculations used in designing the atomic bomb.

The Harvard Mark I computer was operational until it’s “retirement” in 1959.

A very clearly detailed photo of the left side of the IBM Harvard Mark I computer can be seen at

The full-length cabinet bay lineup of the Harvard Mark I can be viewed at

In 1959, Hopper designed the first working computing programming language, called Common Business Oriented Language or COBOL.

COBOL was based on Hopper’s FLOW-MATIC business code language, which she invented in 1955.

The FLOW-MATIC code design called for incorporating English words into the computer’s code-operation commands.

This made it easier to program and execute operations, instead of having computer programs written strictly in all machine language code.

A photograph of the original FLOW-MATIC program code can be seen at

The Mark II daily computer log (with the moth still taped to it) is kept in the History of American Technology Museum, which is part of the Smithsonian in Washington, DC.

You can see the portion of the computer log showing the taped moth (computer bug) at

Hopper is also credited with conceiving the word “debugging,” which is used for describing the work involved in removing computer programming faults.

A photo of her working on the Harvard Mark I computer can be seen at

After World War II, Hopper continued to work with the Mark II, and the new Mark III computer.

She later became involved in the development of the Universal Automatic Computer (UNIVAC), which was the world’s first commercially-used computer.

Grace Murray Hopper was born Dec. 9, 1906 in New York City, NY, and died Jan. 1, 1992.

She is buried in Arlington National Cemetery in Virginia.