Debugging Grace Hopper

Do you know who Grace Hopper is?  And that she has an entomological connection?

I should give her the proper title–Rear Admiral Hopper.  (A biography described her as “Admiral of the Cybersea.”)  Hopper received a PhD in Mathematics from Yale University in 1934, which could not have been easy. She left a faculty position at Vassar to join the Navy in 1943 and was assigned to work on the “Mark I Electromechanical Computing Machine.”  It was 51 feet long, 8 feet high, and 8 feet deep.

From there, she went on to work in academia, industry, and the military, staying on the cutting edge of computing. Her best known innovation is the compiler, but she is also responsible for COBOL, FORTRAN, and many other computing innovations.

Whether or not Hopper was the person that coined the term “computer bug” is a source of some controversy.  The Navy seems to support the idea that it was Hopper that squashed the first computer bug;  there is an actual photo of the offending insect on Hopper’s US Navy webpage:

Moth found trapped between points at Relay # 70, Panel F, of the Mark II Aiken Relay Calculator while it was being tested at Harvard University, 9 September 1947. The operators affixed the moth to the computer log, with the entry: “First actual case of bug being found”. They put out the word that they had “debugged” the machine, thus introducing the term “debugging a computer program”.
In 1988, the log, with the moth still taped by the entry, was in the Naval Surface Warfare Center Computer Museum at Dahlgren, Virginia.

Somehow, “computer moth” just doesn’t have the same resonance.

If you dig a little deeper, though, it appears the use of “bug” to describe a technical problem has a complex history–and in fact, may not have originated with Grace Hopper at all.

“The OED Supplement records sense (4b) of the noun bug (“a defect or fault in a machine, plan, or the like”) as early as 1889. In that year the Pall Mall Gazette reported (11 Mar: 1) that ‘Mr. Edison … had been up the two previous nights discovering a ‘bug’ in his phonograph–an expression for solving a difficulty, and implying that some imaginary insect has secreted itself inside and is causing all the trouble.’….

This meaning was common enough by 1934 to be recognized in Webster’s New International Dictionary: ‘bug, n…. 3. A defect in apparatus or its operation… Slang, U.S.’” (citation)

So, the “actual bug” notation in the lab notebook above probably reflects the amusement of the technician at finding a physical bug, when the word bug was already in use as slang for a problem.

It does appear that the term “debugging” came into use around that time period, but I haven’t seen any evidence firmly tying it to this particular moth.  Oh well.

BTW, The Grace Hopper Celebration of Women in Computing is the largest technical conference for women in computing.  The deadline to apply for scholarships to attend the conference is May 31, 2011.  Go and find some new computer bugs!




Bug_girl has a PhD in Entomology, and is a pointy-headed former academic living in Ohio. She is obsessed with insects, but otherwise perfectly normal. Really!
If you want a daily stream of cool info about bugs, follow her Facebook page or find her on Twitter.

Previous post

Home Births

Next post

Sunday AI: Stately MILF seeks boy toy?


  1. May 21, 2011 at 10:55 am —

    I never had the pleasure of meeting Commodore/Rear Admiral, Lower Half Hopper (At the time she was given the star the rank “commodore” was still in use), but I did see her on the concourse at the Pentagon from time to time when I worked there. It was odd to find someone so elderly in uniform and on active duty. But she still had that look of consummate intelligence in her eyes.

  2. May 21, 2011 at 10:57 am —

    “In 1988, the log, with the moth still taped by the entry, was in the Naval Surface Warfare Center Computer Museum at Dahlgren, Virginia.” That explains why I couldn’t find it at the Harvard Science Center recently, where most of the rest of the Mark II resides. It used to be in the lobby of the Aiken building (where the PDP-1 we used to play Space War on was located), but that got torn down.
    The Boston Skeptics Book Club meets on the lawn outside (in nice weather) and I was hoping to show it everyone :-(.
    Anyway, Yeah Grace Hopper! Woot!

  3. May 21, 2011 at 1:12 pm —

    I saw Adm. Hopper when she gave a dinner talk at a Society of Women Engineers Convention in the early 1980s. It was an engaging speech, and where I first learned that the first computer “bug” was a moth.

    • May 22, 2011 at 11:02 am —

      Yes, she does seem to have promoted the myth a bit herself.

      Really amazing lady–several different papers mention that while it might not be technically correct to say she invented the term “bug” for a problem in technology, she certainly was the first to find an actual insect.

      • May 22, 2011 at 12:42 pm —

        I sensed there was amusement that the problem was an actual insect.

  4. May 22, 2011 at 3:18 am —

    I remember meeting Adm Hopper in 1984. She handed out nanoseconds to all of us during her talk. Amazing lady.

  5. May 22, 2011 at 4:27 pm —

    Grace Hopper was actually a Commodore, not a Rear Admiral. The rank of Commodore was retired with her. Now in the Navy you have Rear Admiral (lower) 1 star and Rear Admiral (upper) 2 star. Like Thoaar I met her in about the same time period. She was an absolutely amazing speaker. She was on the development team for the business programming language dubbed COBOL.

    She provided a historical bridge for computers and programming between the 1940s and the 1980s. This overview really helped us get a perspective on our nerdy world. I wonder who provides a bridge from then to now for today’s computer geeks.

    • May 22, 2011 at 7:39 pm —

      The Navy used to have an “up and out” retirement policy, where you retired one rank over the rank you served in, which is how my uncle became a rear admiral. So maybe that’s how she became Adr Hopper.

      I’ve run across her before doing family research (I’m got some Hopper blood myself), but I had no idea she was such a dynamic person. Which, come to think of it, probably means she’s not related to me :)

  6. May 24, 2011 at 12:39 pm —

    I got to hear her give a commencement speech in 1985 or so. Her theme was “If you see something that needs doing, go for it. It’s easier to apologize than to get permission” I loved her instantly!

Leave a reply