Amazing Grace Hopper

Image of Admiral Grace Hopper
About the Author

Mark Cantrell is a freelance writer based in North Carolina. 

In the beginning, computers were people. When America entered World War II in 1941, a need arose to calculate precise trajectories of ballistic weapons. At the Ballistic Research Laboratory, Aberdeen Proving Ground, Md., a hundred or so women - all college graduates - were enlisted to compute artillery firing tables using mechanical calculators. Their time spent at the task was calculated in “girl-years,” or “kilo-girl hours.” It was a cumbersome, inefficient system, but it was about to change, due in no small part to the efforts of Navy Reserve Lt. j.g. Grace Murray Hopper.

Joining the war effort

After several years teaching mathematics at Vassar College, N.Y., Hopper joined the Navy Reserve in 1943 and was assigned to the Navy's Bureau of Ships Computation Project at Harvard University, Mass. She reported to Navy Cmdr. Howard H. Aiken, an intense, no-nonsense officer who put her to work on the Mark I, America's first digital computer.

At 50 feet long, 8 feet tall, and 8 feet wide, the Mark I was an imposing sight. In contrast to other, single-function calculating machines, the Mark I was a general-purpose computer, adaptable to different tasks. Aiken had designed it to help him calculate formulas more efficiently, calling it “a lazy man's idea.” The Mark I was programmed using punched paper tape loops, the holes in the tape representing binary ones and zeros. Mechanical feelers translated the holes into directions for the machine. Hopper called the process of giving the computer instructions “coding” and was not happy when it later became known as programming.

Early on, each program was written from scratch, a constant “reinvention of the wheel” Hopper considered wasteful of time and effort. She began using notebooks to record snippets of code that could be reused when needed, though they still were entered manually for each program. Hopper called them “subroutines.” Eventually, Aiken assigned her to create a manual for the Mark I, which became the first computer manual ever written. The Mark I proved so much faster and more accurate than manual computation methods that soon its processing time was booked 24 hours a day. No longer did the Navy need to employ rows of women with calculators to compute firing tables; with Hopper's programming, the Mark I could do the job in record time.

Compilers and COBOL

Hopper could have returned to teaching after the war, but by then, she was well aware she was helping to make history, and she stayed with Aiken at Harvard, where she worked on the Mark II and III computers.

In 1949, she went to work for Eckert-Mauchly Computer Corp., helping develop the UNIVAC - Universal Automatic Computer - a fully electronic system created for the Census Bureau and the first computer capable of translating numbers into letters, which set the stage for a revolution in the nascent computer industry.

Hopper realized subroutines now could be stored and assembled by the computer itself, instead of tediously copied from a notebook. She wrote a piece of code, called a compiler, that retrieved and stacked subroutines in the computer's memory to create a program. She later created a more capable version called MATH-MATIC, but the true breakthrough came with her FLOW-MATIC compiler, which for the first time allowed coding in plain English. By 1958, all Navy shipyards were using it.

By then, however, several competing programming languages were in use. DoD realized a standard was needed and established a committee to create one, with Hopper taking a major role. What emerged in 1959 was COBOL - Common Business-Oriented Language - largely based on Hopper's FLOW-MATIC compiler. Like its predecessor, COBOL was a plain-English computer language that made programming more widely accessible - and once more, Hopper had a hand in its creation.

COBOL was a resounding success, in large part because any company wanting to do business with DoD had to use it. One of COBOL's key advantages: It could run on computers made by different manufacturers, which greatly accelerated its adoption by both the military and private industry. By the mid-1960s, Hopper was so famous in Navy circles she no longer had to apply for standard two-week training stints. Instead, at the Navy's request, she spent that time helping naval installations set up their own computing systems. As a teacher, she was finally in her element - until a letter arrived from the chief of naval personnel in 1966: It was time to retire. Although a rebel in the world of computing, Hopper was a faithful naval officer, and on the last day of the year, she reluctantly separated from service.

So much for retirement

Hopper's retirement didn't last long. Seven months later, the Navy called again: Something had to be done about COBOL. In the years since its creation, differing versions of the language had emerged, creating confusion and conflict. Hopper was mustered back into the Navy Reserve and assigned the task of standardizing the Navy's computers, restoring order to its high-level programming languages. The job was to last six months, but she pursued that mission for the next 19 years.

When Hopper retired from the Navy for the third and final time in 1986, at the age of 79, she was the oldest active duty commissioned officer in the Navy. She was awarded the Distinguished Service Medal, one of hundreds of awards she received, on the decks of USS Constitution in Boston Harbor. She promptly went to work as a consultant for Digital Equipment Corp., hitting the lecture circuit to promote careers in computer science.

When she died in 1992 at the age of 85, Hopper left a legacy that will never be eclipsed. Today, her influence has spread around the globe. The Navy today has supercomputers capable of 800 trillion operations a second, direct descendants of the original Mark I. The guided missile destroyer USS Hopper (DDG-70) plies the world's oceans; the Grace Hopper Celebration of Women in Computing conference is held annually; and computer programmers again refer to their job as “coding.” Somewhere, Grace Hopper must be smiling.


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