Grace Brewster Murray Hopper, an early computer scientist, entered the world of computers as a result of the entry of the United States into the Second World War. An associate professor of mathematics at Vassar College when the Japanese bombed Pearl Harbor, she, like many others, wanted to contribute to the war effort, and her choice was to join the navy. Despite multiple obstacles, she became a WAVE at the end of 1943 and was commissioned a lieutenant (j.g.) in 1944. Her entry into the navy was also her entry into the world of computers; she was assigned to the team working on the Mack 1, the first electromechanical computer, at the Bureau of Ships' Computation Project at Harvard University. As quoted by Charlotte Billings, Hopper described responding to the Mack 1 as "the prettiest gadget" that she had ever seen (p. 49). Hopper remained involved with computing and with the navy for most of the rest of her life. Hopper's creative contributions to computing included the development of the first compiler and of the first nonmathematical programming language, developments which, like many creative contributions, came to be taken for granted but which were unthought of – not merely nonexistent – prior to Hopper's development of them.
Hopper was born Grace Brewster Murray in New York City on 9 December 1906, the oldest child of Mary Campbell Van Horne Murray and Walter Fletcher Murray. Her parents subsequently had two other children, Mary Campbell Murray and Roger Franklin Murray II, three and five years younger than Grace, respectively.
In some respects, Hopper's family may seem typical of educated families of the era. Her father was an insurance broker, as his own father had been. Her maternal grandfather, John Garrett Van Horne, was a surveyor. One of her great-grandfathers, whom she had met as a very small child, had been a rear admiral in the navy – a fact which Hopper herself would mention during her navy career.
In other respects, however, they were an unusual family. Walter and Mary Murray believed that their daughters as well as their son should be well educated and should be able to support themselves as adults. They also believed that their son as well as their daughters should be able to perform such homely (stereotypically feminine) tasks as cooking and mending. Both parents served as role models for their children. Walter, despite the loss of both of his legs because of problems with circulation, lived a long and active life, serving as an example of perseverance in the face of potentially daunting difficulties, and treated his disability with wry humor (e.g., joking that he changed his socks only when they became dusty). Mary, like her elder daughter, loved mathematics, but her opportunities for formal study were limited by her era; as Billings (p. 15) noted, "special arrangements" had to be made for Mary to study geometry in high school, and those arrangements precluded her actually sitting in the classroom. Mary also, because of her husband's health problems and her own consequent fear of widowhood, managed the family finances. In both of these ways, she demonstrated to her children that women could be mathematically capable.
All three children graduated from college, and two (Grace and Roger) also earned doctoral degrees. Additionally, all three had careers related to mathematics. Grace was a mathematician and computer scientist, her sister a statistician for an insurance company, and her brother a banker.
Grace remained close to her family as an adult. After she married a man whom she met in Wolfeboro, where her family had a summer home, Grace and her husband went to Europe with her family rather than honeymooning alone. As a young couple, they lived near her parents and also bought a house in Wolfeboro. Although Grace had no children, she was close to the children and grandchildren of her brother and sister.
As might be expected given her parents' attitudes, Grace's childhood activities were not limited to those prescribed by the times for little girls. Although she played with dolls, she also played with construction sets; she was an avid reader; and she was an athlete (her athletic experience later played a role in her development of the first compiler).
In adulthood, Hopper was an inveterate story-teller, and she frequently told a story of an episode in her childhood which both indicates her early interest in things mechanical and foreshadows her later response to the Mack 1 as "the prettiest gadget" she had ever seen. She took apart an alarm clock when she was seven years old. Unable to put it back together, she continued taking apart other alarm clocks, trying to use them as models, until she had disassembled every alarm clock in the house.
Grace received her primary and secondary education at academically rigorous schools in New York City and New Jersey. As an undergraduate at Vassar, Grace majored in mathematics and physics and anticipated her later professorial activities by helping other students with mathematics and science. She was skilled at contriving demonstrations which helped make abstract concepts concrete. One example from her undergraduate days was an occasion when she asked one student to climb into a full bathtub to demonstrate for a group the concept of displacement of water. A later example for which she was famous was her distribution of "nanoseconds" at her lectures; the "nanoseconds," literally pieces of wire approximately one foot long, showed how far an electron could travel in one one-billionth of a second (a nanosecond).
Hopper graduated from Vassar with honors and with a grant to support her continued education. She received both a Master's degree (1930) and the Ph.D. (1934) in mathematics from Yale University. She also married in 1930; her husband, Vincent Hopper, was another academic, an English scholar at New York University.
Hopper began her professorial career while she was a graduate student, appointed an instructor of mathematics at Vassar in 1931. She remained on the Vassar faculty after finishing her doctorate, advancing through the ranks to associate professor by the time she joined the navy in 1943. Her position at Vassar and her husband's at New York University resulted in their living mostly apart, although Vincent did travel to Poughkeepsie on weekends. The Hoppers separated in 1941 and were divorced in 1945.
Although Hopper wanted to join the navy in the aftermath of the attack on Pearl Harbor, she had multiple obstacles to overcome. In the first place, because professors of mathematics were considered to be essential to the war effort, arranging to leave her faculty position at Vassar was a difficulty. Additionally, Hopper was considered too old (at age 35) and too light (at 5' 6" tall, she weighed 105 pounds) to join the navy. Eventually, however, she was permitted to become a WAVE, attended the Northampton Midshipmen's School, finishing first in her class, and was commissioned a lieutenant (j.g.) in 1944.
Hopper's assignment to the Bureau of Ships' Computation Project at Harvard University was her introduction to computers, and she spent the rest of her career working with computers, sometimes with the navy and sometimes in private industry. Her contributions to the development of computer science will be described in a separate section below.
By the end of the Second World War, Hopper had become a lieutenant. She wished to remain on active duty in the regular navy, but this choice was not open to her. Her age was again the problem. Although she did have the option of returning to her faculty position at Vassar (with a promotion to professor), she chose instead to remain at Harvard to continue working with computers.
The end of the war did not mark the end of Hopper's navy career, however. She remained in the naval reserve, and, as a reserve officer, rose to the rank of commander by 1966. In 1966, however, the navy decided yet again that she was too old to serve. As she told the story to Billings (p. 87), she received a letter from the Chief of Naval Personnel informing her that she had "been on reserve duty for twenty-three years, which was more than twenty. 'I knew that,' Grace said. Another paragraph stated she was sixty years old. 'I knew that too,' she said." Against her own inclination, then, she submitted the requested application for retirement.
As had happened twice before, however, the navy's decision in this case was not final. Hopper shortly was recalled to active duty, not simply reserve duty. The specified term of six months was extended and, by its conclusion, had lasted approximately 20 years. During these years, she headed the Programming Languages Section of the Naval Information Systems Division. Also over these years, she rose in rank to commodore.
In 1986, more than 40 years after the navy first had rejected her because of her age (among other reasons), Hopper was again requested to retire because of her age, this time for the last time. At her retirement, she held the rank of rear admiral; she was not only the oldest serving officer but also the only former WAVE on active duty. Hopper returned to the private sector on her retirement from the navy. The value that she herself placed on her navy service is revealed not only by the length of her service but by her habitually closing her lectures with a comment on "the privilege and responsibility of serving very proudly in the United States Navy," as she put it in a keynote address published in 1981.
When Hopper was discharged from the navy at the close of the Second World War, she remained at Harvard so that she could continue working with computers. Over the next few years, she, along with the other members of the team, worked on the Mack 2 and the Mack 3, the successors of the "gadget" she had found so appealing in 1944. Because remaining at Harvard was not a viable option for the long term, though, Hopper moved into the private sector, going to work for the Eckert-Mauchly Computer Corporation; she remained with this company, through mergers and takeovers and the accompanying name changes, until her 1971 retirement from what had become the Sperry Corporation. By 1971, of course, she had for several years been back on active duty as a naval officer.
After her second lengthy term of active-duty service, lasting from the mid-1960s through the mid-1980s, Hopper, the navy's opinion notwithstanding, did not consider herself ready to retire. Thus, she returned to the private sector as a senior consultant at Digital Equipment Corporation. In that capacity, she continued to travel and to lecture for the next several years, until 1990. She thus was active nearly until her death on 1 January 1992. Befitting her years of service and her dedication to the navy, she is buried in Arlington National Cemetery.
When Hopper joined the navy and was assigned to the Bureau of Ships' Computation Project, computers were in their infancy. The Harvard team which she joined was working on the Mack 1, the first electromechanical computer, and she was only the third person (and the first woman) to program this computer. This early computer stands in remarkable contrast to computers of the twenty-first century; a huge machine, it was also hugely slower and less powerful than even an inexpensive modern desk-top computer. Processing speed of readily available twenty-first century personal computers is measured in megahertz or gigahertz; the Mack 1 performed three operations per second. By the standards of the era, however, and in contrast to human computers, the Mack 1 was impressively rapid.
Human–computer interactions in the mid-twentieth century in many respects were even more different from those of the twenty-first century than were the machines themselves. Computer users of the twenty-first century are accustomed to user-friendly operating systems and point-and-click environments. The programmers of the Mack 1, in contrast, wrote the instructions to the computer in machine language. Sets of instructions to perform specific tasks (programs, in the modern parlance) as well as the data to be processed were punched on paper tape, not stored in the computer. The paper tapes, however, could be kept and could be reused when needed. By making such a collection, Hopper and her colleagues began building a library of programs.
Probably more importantly in terms of the development of computer programming, Hopper and her colleagues collected standard sets of instructions for sets of operations which were common to multiple programs. In the abstract, these standard instruction sets were equivalent to what modern programmers think of as subroutines. In their instantiation, however, they were primitive compared to their modern descendants. Rather than being built into the software or the hardware, these "subroutines" were written on paper and collected in notebooks. In order to use one, a programmer had to copy it by hand into the program being constructed. Although this procedure reduced the mental labor of programming substantially, there still was ample room for human error; in fact, there were now two separate occasions for transcription errors, first in the process of copying subroutines into programs as they were written, and second, as always had been the case, in keypunching the programs once written.
It occurred to Hopper that the problem of transcription errors (along with other problems) could be addressed by using the computer itself to make copies of stored subroutines. This insight eventually led to her development of the first compiler in the early 1950s, while she was working at Eckert-Mauchly. Her idea – and her implementation of it – flew in the face of the conventional wisdom that "computers could only do arithmetic," as she expressed it in the 1981 keynote address (pp. 13–14). As she described it in the now classic paper, "The Education of a Computer," by writing this first compiler, called the A-0, she made the computer into its own programmer.
Her refusal to accept conventional wisdom and her rejection of the way things were as the only way they could be were persistent characteristics of hers, and she encouraged others to take unconventional tacks as well, often saying "It is easier to ask forgiveness than it is to get permission" (or some variant of this line). Her office clock, which was numbered and which ran counterclockwise, was a concrete example of her acceptance and her encouragement of novel ideas.
Another characteristic of this first compiler remained impressive – and startling – to her colleagues even after they had accepted that compilers were possible, and that was that the A-0 was a single-pass compiler. As Hopper described the problem in a 1980 oral-history interview,
obviously you couldn't do that, because you'd run into a place where in the flowchart, for instance, you could have two kinds of tests. One would jump back to somewhere you'd been and you knew where you put that program piece, but you would have another test that jumped forward and you haven't processed that yet, so you didn't know where it was going to go (p. 7).
Hopper solved the problem of not knowing where to jump forward to by analogy to a very different domain, using a memory of her experience playing girls' basketball in high school. She built into the compiler a "neutral area," and, when the compiler needed to jump forward to a place not yet specified, it would jump instead to the neutral area and put a flag in this neutral area; this flag then would trigger a jump to the appropriate operation once the compiler had progressed that far.
A-0 was a major advance in computer programming, both conceptually and practically. It still was written in machine language, though. In the 1950s, with computers increasingly in commercial use and in use for functions beyond computation, the requirement that computer instructions be written in machine language was hampering the development of needed programs. Hopper was one of the first to consider using forms which looked like natural language (strings like count and divide) for writing computer programs. For all that programming and programming languages are foreign to most twenty-first century computer users, Hopper's and others' development of high-level programming languages might be considered first steps in the direction of user-friendly computers. Hopper herself, in a 1969 oral-history interview, attributed both the development of the initial compiler and the development of high-level programming languages to the realization that "we had to make it easier for people to use computers" (no page number).
Like the original idea of a compiler, this idea flew in the face of established wisdom. Everyone knew that "computers couldn't understand English words," as Hopper later put it in the 1981 keynote address (p. 16). Hopper, of course, also knew that computers could not understand English. What was required, however, in her view, simply was another version of a compiler, in this case one which would translate instructions using words (which made sense to people) into machine language (which the computer could process). This new compiler, B-0, was introduced in 1955. With this development, working computer programs could be written using such statements as "INPUT INVENTORY FILE A; PRICE FILE B" and "OUTPUT PRICED INVENTORY FILE C."
Hopper and her team wrote other versions of the compiler which used French or German words rather than English. This, however, seemed from her later description to have been considered carrying innovation too far for the corporate management. As she said in the 1981 address (p. 17),
it was absolutely obvious [to management] that a respectable American computer, built in Philadelphia, Pennsylvania, could not possibly understand French or German! And it took us four months to say no, no, no, no! We wouldn't think of programming it in anything but English.
Although Hopper's FLOW-MATIC (a name assigned by the marketing department) is no longer in use, it was and is important for several reasons. It was one of the first high-level programming languages to be widely used, and it was the first which was specialized for nonmathematical uses. More importantly, FLOW-MATIC was not only the precursor of but the model for COBOL (Common Business Oriented Language), one of the most important programming languages of the twentieth century and still important in the twenty-first century.
The development of COBOL has often been attributed to Hopper. Although this attribution is false, Hopper's influence on COBOL, both at its outset and later, was substantial. For example, she belonged to the group which initiated the development of COBOL and provided technical advice to the group which actually constructed the language. Jean Sammet, who was a member of the latter group, wrote in 2000 that
without the existing practical use of Flow-Matic, I doubt that we would have had the courage to develop a language such as Cobol (p. 31).
Over the years after its release, as COBOL was used for various purposes in various sites, programmers at different sites modified the language to fit it to their local needs. The small-scale utility of the resulting different versions of COBOL created problems on a larger scale: Programs written at one site in one version of COBOL might not run – or might not run correctly – at other sites where COBOL had been modified differently. In other words, COBOL ceased to be effectively a common language, becoming instead a family of related languages.
It was to rectify this situation that Hopper was recalled to active duty in the navy in 1967 (only months after she had reluctantly retired from the naval reserve). Making yet another major creative contribution to the development of high-level programming languages, Hopper and the team she directed developed procedures for testing the various versions of COBOL to ensure consistency of performance across the variants. These procedures might be considered to stand in the same relation to COBOL as does the Academie Francaise to the French language.
Hopper's contributions to the navy and to computing were recognized by the navy, by the computer science community, and by the broader community in many ways over the years, beginning early in her career. She was awarded the Naval Ordnance Development Award (1946), the Computer Science Man of the Year award (1969, the first year it was awarded), and the National Medal of Technology (1991). She was named a Distinguished Fellow of the British Computer Society in 1973, the first woman and the first American to be so honored. Her namesakes include the Grace Murray Hopper Award (established 1971; awarded annually at the meeting of the Association of Computing Machinery), the computer center at Brewster Academy (a private school in the community where both she and her parents had summer homes), the Grace Murray Hopper Service Center (a naval data processing center in California), the USS Hopper (a highly-computerized destroyer), and the Grace Hopper Celebration of Women in Computing (first held in 1994).
Grace Hopper grew up in a family with some unconventional attributes, which may have contributed to her own acceptance of alternatives to the usual ways of being and doing. In particular, her mother offered a model of a mathematically competent woman, defying a stereotype much stronger early in the twentieth century but still strong in the early twenty-first century.
Hopper's story of her dismantling of every alarm clock in the house is emblematic of multiple characteristics which are likely contributors to her creative accomplishments as an adult. In the first place, she was curious, and she acted on that curiosity, setting out to discover for herself how an alarm clock went together. Second, she was persistent: She did not stop trying to solve the problem until she ran out of alarm clocks. The story itself is representative of another aspect of her creativity, her consistent use of her own history, personal and professional – her story-telling – to make and to illustrate her points.
Two other characteristics likely to have contributed to her creative accomplishments are distinct but closely related: She had a capacity for moving between the abstract and the concrete, and she had a knack for analogical/metaphorical thinking. Her practical demonstration of the displacement of water to her fellow students at Vassar and her use of lengths of wire to make the concept of a nanosecond comprehensible to those to whom she lectured both are examples of her skill at making the abstract concrete (her story-telling perhaps also falls under this aspect of her creativity). The nanosecond example also demonstrates her use of an analogy between spatial extent and temporal duration, an analogy implicit in much ordinary language usage but made explicit by Hopper's wire "nanoseconds." Her use of an aspect of the rules of girls' basketball as played in her youth to suggest a solution to the problem of forward jumps when compiling a program goes from the concrete to the abstract and also draws on a novel analogy.
Hopper's refusal to be bound by the way things traditionally were done or even by what "everyone knew" also contributed to her creative accomplishments. Both in writing the first compiler and in constructing an early high-level programming language using English words, Hopper made a computer do what "everyone knew" a computer could not do. Last, but not least, in both these cases, Hopper identified a state of affairs of which others also must have been aware as a problem to be solved. Her identification of the problems may be more truly a hallmark of her creativity even than her solution of them. Hopper herself, discussing her achievements in an oral-history interview in 1969, said about A-0 and B-0 that
the realization of what was needed and what could be done was more important than the actual doing of it (no page number).
In some cases, particularly on large-scale projects, creativity may emerge from collaborative rather than from identifiably individual activity. That Hopper and her Mack 1 colleagues realized that programs and subroutines could be collected and reused and that they made and used these collections may be instances of collaborative creativity, as may the later development of validating procedures for COBOL developed by Hopper and her team in the 1960s.
Hopper's frequently offered advice to dare and to do (Aude et Effice, in the original and in the form used for the emblem of the USS Hopper) was advice which her career exemplifies; Hopper practiced what she preached. She was intellectually daring and highly effective in contributing to the development of her chosen world of computers and computing.
Analogies; Families and Creativity.
- Grace Hopper: Navy Admiral and Computer Pioneer 1989 Enslow Hillside, NJ.
- Only the Limits of Our Imagination: An Exclusive Interview with Rear Adm. Grace M. Hopper Amazing Grace 1986/2002 http://www.chips.navy.mil Retrieved from.
- The education of a computer Reprinted in the Annals of the History of Computing 9 1952/1988 272-281 http://www.computer.org/publications/dlib Retrieved from.
- Interview by Uta C. Merzbach Computer Oral History Collection 1969–1973, 1977 1969 National Museum of American History, Smithsonian Institution http://invention.smithsonian.org/resources/fa_comporalhist_index.aspx January 7.
- Keynote address History of Programming Languages 1981 Academic Press New York.
- Commander Aiken and my favorite computer Making Numbers: Howard Aiken and the Computer 1999 MIT Cambridge, MA http://www.netlibrary.com Retrieved from.
- The contributions of Grace Murray Hopper to computer science and computer education Dissertation Abstracts International – A 5504 1994 879 (University Microfilms No. 9424392).
- Oral History of Captain Grace Hopper 1980 http://archive.computerhistory.org/resources/text/Oral_History/Hopper_Grace/102702026.05.01.pdf Retrieved from.
- Grace Brewster Murray Hopper: A woman who dared and did Women of Vision: Their Psychology, Circumstances, and Success 2007 Springer New York.
- The early history of COBOL History of Programming Languages 1981 Academic Press New York.
- The real creators of Cobol IEEE Software 172 2000 30-32.
- Improbable Warriors: Women Scientists and the U.S. Navy in World War II 2001 Naval Institute Press Annapolis, MD.
- Grace Hopper: Admiral of the Cyber Sea 2004 Naval Institute Press Annapolis, MD.
(born Dec. 9, 1906, New York, N.Y., U.S.—died Jan. 1, 1992, Arlington, Va.) U.S. mathematician and rear admiral. She received a Ph.D. from Yale Uni
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