There was a time when the work of computer programming was dominated by women. But like Ada Lovelace and Grace Hopper, the six women programmers of the ENIAC project made contributions to the field of computer science that were little appreciated at the time. In fact, after Jean Jennings and Betty Snyder had worked out troubles that might have sunk the public unveiling of the first electronic general-purpose computer, they weren't even invited to the celebratory dinner. But with the benefit of years, history has become kinder to these technical pioneers. The word is getting out. (For more on Lovelace, see Ada Lovelace, Enchantress of Numbers.)

The Playing Field Levels

During the height of World War II, the U.S. Military was in desperate need of accurate firing tables, ballistics calculations that would give precision to aerial bombing as well as ground-based cannon and missile fire. The ENIAC (and later the EDVAC) was built for the U.S. Army's Ballistic Research Laboratory by J. Presper Eckert and John Mauchly. It had 17,468 vacuum tubes and 7,200 crystal diodes – it was a large and complex machine. It was powerful, but it had to be programmed.

In the 1930s, women were often better educated than men, according to historian Dr. Kathy Peiss of the University of Pennsylvania. Half of college students were women, but their range of opportunities was limited. World War II changed that. Opportunities for women expanded. Between 1940 and 1945, 50 percent more women entered the work force.

This was largely because the men were off to war. According to Jennifer S. Light of Northwestern University, “World War II was an opportunity for many women to leave their homes and take on jobs in a variety of industries.” Many women, symbolized by Rosie the Riveter, went to work in factories. Women with mathematical training were needed for something just as important: ballistics computing.

Drawn from these ranks, six women were sent to Aberdeen Proving Grounds to work on the ENIAC. These were Jean Jennings (later Bartik), Betty Snyder (later Holberton), Marlyn Wescoff (later Meltzer), Kathleen McNulty (later Mauchly Antonelli, as she would eventually marry one of the project leaders, John Mauchly), Frances Bilas (later Spence) and Ruth Lichterman (later Teitelbaum). Their differences in religious and cultural background made for an interesting team dynamic. (To learn more about the history of programming, see The Pioneers of Computer Programming.)

Everyone Has a Story

Jean Bartik (born Betty Jean Jennings) grew up as a farm girl in rural Missouri. But in an interview in the documentary “Top Secret Rosies: The Female Computers of World War II,” Jean said she “never wanted to live on a farm.” She wanted to get out of Missouri and “go to some place big.” Perhaps the most famous of the six women programmers of ENIAC, Bartik went on to work on the BINAC and UNIVAC I computers, and lectured about her experiences until her death in 2011.

The group was divided into three special teams. Marlyn Wescoff and Ruth Lichterman, whose experience was on desktop calculators, mastered certain ENIAC functions and helped prepare ballistics programs. Frances Bilas and Kathleen McNulty, both mathematics graduates of Chestnut Hill College in Philadelphia who had operated Moore School's Differential Analyzer, worked together on complex equations. Jean Jennings and Betty Snyder tackled the ENIAC's Master Programmer and led the preparation for demonstration of the ENIAC. The use of subroutines was the idea of Kathleen McNulty: “We can use a master programmer to repeat code.” She would continue to work on computer design and implementation with her husband, John Mauchly, for many years.

A notable story about Bartik and colleague Betty Snyder Holberton relates to the preparation for the ENIAC unveiling. Tasked by Captain Herman Goldstine to program the computer for a demonstration, the two women were stymied on the night before the big event. It was Valentine's Day, but they did not have boys on their minds. They took public transportation home to sleep on it. The solution came to Betty in the middle of the night. She promptly took the early train back to work, flipped the right switches, and fixed the problem. Bartik later recalled that “Betty could do more logical reasoning while she was asleep than most people can do awake.”

All of them had worked in the technical industry at a time when the word “computer” applied to a person, not a machine. In the early years, mathematically capable women worked in crowded rooms seated in front of noisy calculating machines. But only six of these “computers” are now remembered as the talented women programmers of ENIAC.

Lasting Contributions and Recognition

Their work as “computers,” and later ENIAC programmers, was not easy. The Army needed those firing tables – and fast! This often called for double and even triple shifts. But the women were young, and still managed to find time to enjoy themselves. Jean Bartik remembered her time on the ENIAC as one of the happiest of her life. “We never ran out of things to say to each other,” Kathleen McNulty recalled.

But it was not all fun and games. Lives hung in the balance. Speaking of the many forgotten women in the computing industry, military historian Dr. William F. Atwater said that “without their contribution to the war effort, we would have lost World War II.” Women took the roles of code breakers, ballistics calculators, and machine programmers. The ENIAC six are prime examples of that effort.

History now remembers the contributions of the computer legends Ada Lovelace and Grace Hopper. But the secret work of these six women was all but lost to the world until 1986. The ENIAC was able to calculate in 15 seconds missile trajectories that would have taken 40 days by human effort. A paper written by Harvard graduate student Kathy Kleiman was perhaps the first to tell the world the story. That was followed by an article by Wall Street Journal writer Tom Petzinger called “History of Software Begins with the Work of Some Brainy Women.”

All six women were inducted into the WITI Hall of Fame in 1997. Bartik received numerous honors for her work, including the IEEE Computer Pioneer Award, and she was made a fellow of the Computer History Museum in Mountain View, California. Her story is told in Walter Isaacson's “The Innovators,” as well as in her own book “Pioneer Programmer: Jean Jennings Bartik and the Computer that Changed the World.”


Software programming today seems to be in the hands of young, tech-centric men. But in the early days, men were more concerned about the hardware. Calculating and programming were akin to clerical work. Today we know much more about the importance of what these bright women accomplished. Men may have made the machines, but as Dr. Light put it, these women “were the ones who made the machines work.”

(To learn more about the story, watch these interviews of Jean Bartik from the Computer History Museum: 1) Jean Bartik and the ENIAC Women; 2) Jean Jennings Bartik - ENIAC Pioneer. You can also follow the ENIAC Programmers Project, which was established by Kathy Kleiman to tell their inspiring story.)