Before computers became a part of everyday life, programming was a completely different challenge. There were no modern keyboards, computer screens, or familiar coding languages. Instead, some of the earliest electronic computers required people to connect cables, adjust switches, and carefully organize complicated mathematical instructions.
During World War II, a remarkable group of American women helped solve this challenge. Their work contributed to the development of computer programming, yet their achievements received little public attention when they first made history.
Their story reminds us that the history of technology is not just about machines. It is also about the people whose skills helped those machines become useful.
A Nation Facing a Mathematical Challenge
During World War II, the United States military needed accurate mathematical calculations to help determine the trajectories of artillery shells.
These calculations were difficult and time-consuming. Teams of human computers, many of them women, worked with mathematical tables and calculating machines to process the enormous amount of information required.
At the University of Pennsylvania’s Moore School of Electrical Engineering, engineers J. Presper Eckert and John W. Mauchly worked on a new machine designed to perform these calculations much faster.
The machine became known as ENIAC, short for Electronic Numerical Integrator and Computer.
Funded by the U.S. Army, ENIAC was developed between 1943 and 1945. It was one of the earliest large-scale electronic general-purpose digital computers in the United States.
But building the machine was only part of the challenge. Someone also had to figure out how to make it perform complicated calculations.
Six Women Took on an Unfamiliar Challenge
In 1945, six women were assigned to work on programming ENIAC.
They were:
Kathleen McNulty
Jean Jennings Bartik
Frances Bilas Spence
Betty Snyder Holberton
Marlyn Wescoff Meltzer
Ruth Lichterman Teitelbaum
These women had mathematical backgrounds, but programming a machine like ENIAC was a new kind of work.
The computer did not operate like the devices people use today. Programming it involved understanding its internal structure and configuring its switches and cables to carry out a particular sequence of operations.
The women had to learn how the machine worked and develop practical methods for making it perform calculations correctly.
There was no modern programming environment to guide them. They relied on mathematical knowledge, careful reasoning, experimentation, and teamwork.
Their work helped establish techniques for operating and programming early electronic computers.
Programming Without Modern Tools
Imagine being asked to operate a powerful machine without a familiar keyboard, a screen, or a modern programming language.
That was the challenge these women faced.
ENIAC occupied an entire room and contained thousands of electronic components. Its configuration had to be changed for different computational tasks.
The women translated mathematical problems into detailed instructions that the machine could execute. They worked with technical diagrams and learned how the computer’s different sections interacted.
Finding an error could require considerable patience. A mistake in the configuration or sequence of operations could prevent a calculation from producing the expected result.
Through experience, the women developed systematic approaches to organizing instructions and operating the computer.
Their contribution was not simply pressing buttons on a finished machine. They helped determine how ENIAC could be programmed to solve practical problems.
This distinction is important. A computer becomes useful not merely because its hardware exists, but because people understand how to direct its operations.
The Work Behind the Machine
The development of ENIAC involved many people with different responsibilities.
Engineers designed and constructed the hardware. Mathematicians and human computers helped define the calculations that needed to be performed. The women programmers developed ways to configure the machine so that it could carry out those calculations.
These responsibilities were connected, but they were not identical.
The six women helped bridge the gap between the computer’s physical design and its practical use.
Their work also demonstrated that programming required more than mathematical ability alone. It demanded logical thinking, careful planning, technical understanding, and the ability to identify and correct errors.
As electronic computers developed, these skills became increasingly important to the emerging field of computer science.
Why Their Achievement Was Overlooked
When ENIAC was publicly demonstrated in February 1946, attention focused heavily on the machine and its engineers.
The women who had programmed the computer did not receive comparable public recognition at that event.
Their contributions remained less visible than those of many people associated with the development of early computing.
This was part of a wider historical pattern. During the early decades of computing, women performed important mathematical and technical work, but their responsibilities were not always recognized as central to technological innovation.
The history of these six programmers became more widely known decades later, as researchers revisited the records of early computing and brought their achievements to a broader audience.
Their story illustrates why historical recognition matters. When the people behind a major invention are left out of its story, our understanding of how that invention developed remains incomplete.
A Legacy That Reached Beyond ENIAC
The six ENIAC programmers helped establish practical approaches to programming at a time when the field was still taking shape.
Several continued to contribute to computing after their work on ENIAC.
Jean Jennings Bartik, for example, worked with early computer systems after the ENIAC project. Betty Snyder Holberton later became an important figure in software development and helped shape early programming practices.
Their careers formed part of a larger story in which early computer operators and programmers helped transform electronic computers from experimental machines into practical tools.
Modern programming looks very different from configuring cables and switches in a room-sized computer. Yet the need to break complex problems into precise instructions remains fundamental.
The women who worked on ENIAC helped demonstrate what skilled programmers could accomplish, even when the tools available to them were unfamiliar and difficult to use.
Remembering the Women Who Helped Shape Computing
Today, computers influence medicine, education, communication, transportation, science, and almost every part of daily life.
It is easy to focus on powerful machines and the people who designed their hardware. But the history of computing also depends on those who figured out how to make those machines work.
The six ENIAC programmers faced a technology that was still being understood. Through mathematics, experimentation, and collaboration, they helped develop methods that contributed to the foundations of computer programming.
Their story deserves to be remembered not simply because they were among the early women in computing, but because their technical work mattered.
The history of American innovation is incomplete without the people who helped turn complicated machines into tools that changed the world.
The story of the ENIAC programmers is one important part of that history.
Sources and Historical References
The following sources were consulted to verify the historical information in this article.
Smithsonian American Women’s History Museum — Human Computer Project
Smithsonian: Human Computer Project
National Women’s History Museum — Women and Computing
Women and Computing
Smithsonian National Museum of American History — ENIAC Accumulator
Smithsonian: ENIAC Accumulator
Computer History Museum — Women in Computing Tour
Computer History Museum
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