Refrigerator Ladies: The First Computer Programmers

March 8, 2018 Liz Huang

The story of ENIAC, the first completely electronic computer, and the women who made it possible.

Photo courtesy of Wikimedia Commons.

In the 1980s, a young Harvard undergraduate named Kathy Kleiman was doing research when she stumbled upon an old, fairly well-known photograph of the first all-electronic computer. In it, the photo showed men and women demonstrating the machine. When Kleiman looked closer, the photo only identified the men — not the women. Who were these women? She asked. What was their role? Kleiman took these questions to a university historian, who told her the women in the picture were models that were hired to pose in front of the machine. They were dismissed as “Refrigerator Ladies.” To Kleiman, this didn’t sit right, there had to be more to the story. And so, Kleiman started digging — what she would find about these women, who they were, and their accomplishments would be the furthest thing from models hired to pose in front of a machine.

Part I. Betty

Jean “Betty” Jennings Bartik / Photo courtesy of Northwest Missouri State University.

Being a programmer was never part of Jean Jennings Bartik’s plan. The sixth of seven children, Bartik, then known as Betty, grew up in a poor, large northwestern Missouri family during the heart of the Great Depression.

Growing up, Bartik never thought far beyond the confines of her small, rural town of Stanberry. She spent her days playing softball, riding horses, and fantasizing about a future career in nursing so that she could work with her brother Bob, who wanted to be a doctor.

Bartik, however, had a natural aptitude for math and graduated salutatorian of her high school class. In 1941, she entered Northwest Missouri Teachers College, and at the end of her first quarter, Pearl Harbor was bombed by the Japanese and the United States entered into World War II. “We realized our lives had changed forever,” Bartik would later recall in her memoir. “School seemed irrelevant for many in the face of war.”

World War II shifted the course of the nation from 1939–1945, upending societal norms and drastically altering the ways of life of millions of Americans. Japanese-American citizens in the west were stripped of their rights and detained, food and supplies were strictly rationed, and men — who had long dominated America’s workforce — were drafted into service.

There was no choice but to have women enter the workplace in order to support the war effort. This left American women in an unfamiliar position. For the first time, the domain of women extended far beyond the home and found its way into the factories and other traditionally male jobs. It was during this time that famous iconography of Rosie the Riveter and the American working woman made its way into the public conscious. It is estimated that nearly 6.5 million women entered the workforce during this time, and by the time the war was over, nearly one in every four married women worked outside the home.

As Bartik’s graduation neared, she began to wonder about what she might do after receiving her degree. Many told her to teach, as it was the natural progression from graduating from a teacher’s college, but it wasn’t what Bartik wanted. It was her calculus professor, Dr. Ruth Lane, that pushed her to pursue a career beyond teaching, and would suggest positions at IBM for Bartik to pursue. “Dr. Lane came in [one day] with a recruiting letter soliciting math majors to be ‘computers’ on a project at the University of Pennsylvania.” Bartik would write in her memoir, “and I wanted to see something of the world.” So, Bartik applied, and was soon met with a telegram job offer with the instructions to ‘Report as Soon as Possible,’ and so, she went to Philadelphia by steam train, with little idea of what was to come.

“She wanted adventure,” her son Timothy would say years later to the New York Times, “and so she got it.”

Part II. The Computers

Following the entrance of the United States into World War II, it became clear that the army had a conundrum. They did not know how to hit a distant target with their long and medium reach cannons — something that was imperative in the ongoing war.

“Weather had a big impact on the arc and trajectory of the missile of the cannon,” said Kleiman in her documentary film The Computers. “There was a differential calculus equation, and if you could put in one set of weather conditions for one gun and one missile, you could calculate the trajectory and could figure out where to shoot the gun, and the army needed thousands of these calculations.”

According to Kleiman, these calculations were complex and not only relied on where the target was going and the weather, but also took into account factors such as humidity, the curvature of the earth, and others. No single data point of information was left unconsidered. This calculation used differential analyzers (a limited analogue calculator) but was inaccurate in many respects. However, it was the most precise option available at the time.

The job was slow — completing the long calculations took on average around 40 hours.

Like many industries in the United States during wartime, the army was facing a shortage of male mathematicians to do these calculations, with so many at war or working on projects at Los Alamos or on the Manhattan Project. So, the army, a male-dominated institution since its inception, begrudgingly began to hire women to take on this enormous and unrelenting task.

Bartik and many women like her arrived at The Moore School at the University of Pennsylvania and were handed a Monroe hand calculator, shown how to do the calculation, and put to work on the ballistics tables. The job was slow — completing the long calculations took on average around 40 hours. Once finished, the calculations would then be relayed to a firing officer, who would check a table to determine where and at what angle to fire the cannon.

Even with a massive workforce of over 100 women working around the clock, the process was too slow and the army was finding itself falling behind. Speed was vital, and with the cannons remaining in states of un-use due to the slowness of hand calculations, there was no other choice but to make a game-changing pivot.

This is where the power of the computer came in.


The ENIAC Machine / Photo courtesy of Creative Commons.

In 1943, two men, John Mauchly and J. Presper Eckert, along with the United States army, had begun designing and engineering a system called the Electronic Numerical Integrator and Computer, or ENIAC. Mauchly and Eckert were University of Pennsylvania engineers interested in computing machines and their mechanics, and they had an affinity for tinkering with electricity and wiring. Convinced that the quickness of electrons made it ideal for computational devices, Mauchly and Eckert began exploring the possibility of an electronic calculator made from wiring and vacuum tubes. After exploring all the possibilities — according to Scott McCartney’s 1999 book ENIAC, they decide to — in Eckert’s words — “do it whole hog and make everything in sight digital.”

The pair proposed a seven-page document called “The Use of High-Speed Vacuum Tube Devices for Calculation” in the months following Pearl Harbor which detailed their plan for a revolutionarily quick electronic calculator.

The ENIAC had its fair share of doubters. At the time of proposal, this device was so improbable that according to McCartney, it was instantly ignored by the deans at the University of Pennsylvania. Other academics and advisors from institutions such as MIT proclaimed it would never work and dismissed it almost immediately.

The Army however, was running out of time and needed to take a chance. Thus, due to sheer desperation for a solution, Mauchly and Eckert were granted $61,700 (almost a million dollars in 2018) for their first six months of initial work to build the ENIAC.

After years of around-the-clock work to get the machine ready for use in the war, the last of the ENIAC was completed and ready to go following the liberation of Paris by US Troops in August of 1944. But the Army and the team at the University of Pennsylvania faced another problem — now that the machine was built, who would run and program it?

Part IV. “A Son of a Bitch to Program”

In June of 1945, a memo was circulated amongst the “computers” working on the differential analyzer: There was a new machine being built at the University of Pennsylvania, and they were looking for math majors to work on it. Bartik, along with countless other women applied, and at the end, five programmers were chosen; Kay McNulty, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, and Bartik herself, with Frances Bilas joining as a sixth programmer later on.

“We were given three-by-four-foot block diagrams of the ENIAC circuits and told to study them.” Bartik recalled in her memoir “I had never read a block diagram in my life.”

The women ranged in age from 20 to 28, and had a range of skills that made them the perfect candidates for these roles. According to Bartik, Snyder was a longtime computer, who had been on special assignments throughout the duration of the war. McNulty had “experience cranking shafts and shifting gears on a differential analyzer,” Wescoff had immense accuracy in her calculations, and Lichterman, the youngest of the group, brought her enthusiasm and tenacity.

Photo courtesy of Wikimedia Commons.

There was no clear plan for this group. The work differed greatly from what Bartik and her colleagues were used to. Despite a two-month-long crash course in plugboards and running the card punching equipment used in the ENIAC, the work in actually getting the machine to work was ground-breaking and had no precedent. Thus, it was up to the “computers” to understand how to distill the extremely complicated equation that was used to calculate the missile trajectories into a way that the ENIAC could be used. “We were given three-by-four-foot block diagrams of the ENIAC circuits and told to study them.” Bartik recalled in her memoir “I had never read a block diagram in my life.”

Frances Bilas Spence feeding punch cards into the ENIAC / Photo courtesy of Wikimedia Commons.

The programmers spent countless days and nights studying the diagrams to understand how to use the ENIAC to perform trajectories. They would bounce ideas between each other and off of the hardware engineers on how to use the machine, and, more importantly, on how to get it to do what they wanted. The ENIAC had various units, transmitters, and readers that collectively needed to be told what to do, and if that was figured that out, they could use it to calculate trajectories. “It was a son of a bitch to program.” Bartik now-famously said.

It was McNulty who had the breakthrough. “[One day,] Kay exclaimed, ‘I know how! We use the master programmer to reuse code.’” recalled Bartik. They figured that by using the stepper switches of the master programmer, which was the control unit of the ENIAC, they could manipulate the machine into if/then statements, which had previously been deemed impossible.

This breakthrough was revolutionary, and the programmers — by way of hand-wiring the machine via the use of cables and switches — were able to create and maintain a program that allowed the ENIAC to calculate trajectories electronically, something that had previously only been done by hand. However by this point, the war had ended, and the machine wasn’t needed. But the achievement remained: calculations that once took hours upon hours now took seconds. Even though it wasn’t abundantly clear at the time, the programmers had done something extraordinary.

As a result of this, the ENIAC programmers were the first programmers in the world. They accomplished something that had never been done before, and paved the way for future technologies in computing and otherwise. As soldiers returned home following the end of the war, it became clear that the role that this group held was irreplaceable, and despite the Army’s best efforts, no returning soldier had the ability to do what these women had done.

On February 15, 1946, the ENIAC was unveiled to the public as the first ever computer to successfully run a program. The Army held demonstrations to the press, scientists, and dignitaries — the machine was heralded at the time as historic and game-changing, running front page in newspapers across the nation.

Photo courtesy of Wikimedia Commons.

In the years following, many of the programmers would go on to work on other projects in computer programming or otherwise. They were given little recognition — if at all — of their accomplishments. Mauchly and Eckert, the team of male hardware engineers and The United States Army were given immense credit for their work, and the programmers, the ones who had played a vital role in making this all possible, faded into obscurity.

Part V. Legacy

When Kleiman found out the rich and important legacies of the ENIAC programmers, it became imperative to her that their stories would not live and die by a photograph, and that these women — the first computer programmers — would not be immortalized as refrigerator ladies but as the pioneers that they were.

In the 1990s, Kleiman was able to speak to most of the core six programmers and give life and validity to their stories and accomplishments. Through the work of Kleiman and others, proper recognition was given — albeit 50 years late — to Bartik, McNulty, Wescoff, Lichterman, Snyder, and Bilas.

For Bartik, the one-time farm girl who helped give rise to an entirely new technology and pioneered an entire industry, her alma mater (now known as Northwest Missouri State University) opened the Jean Jennings Bartik Computing Museum in her honor in 2003, her legacy and life’s work finally cemented.

Though the women of the ENIAC were able to find eventual redemption, most pioneering women throughout technology and computing have been completely overlooked or have had their accomplishments go unrecognized. Even known names such as Katherine Goble Johnson, Jean Sammet, and Grace Hopper still do not hold the weight that their male counterparts do, despite the importance of their contributions.

For Kleiman, the impact of the ENIAC programmers is deeper than the technology they pioneered. “The ENIAC programmers story inspired me to stay in computing at a time when every other signal in society was urging me to turn away,” said Kleiman. “It is my great hope that the ENIAC programmers story will throw open the doors of computing to all.”


Bartik, J. (2013). Pioneer Programmer: Jean Jennings Bartik and the Computer that Changed the World. Truman State University Press.

Kleiman , K. (Producer). (2016). The Computers[Video file]. Retrieved from

Levy, S. (2013, November 01). The Brief History of the ENIAC Computer.

Light , J. S. (1999). When Computers Were Women . Technology and Culture ,40(3 ), 455.

Lohr, S. (2011, April 07). Jean Bartik, Software Pioneer, Dies at 86. Retrieved March 07, 2018, from

McCartney, S. (2001). ENIAC: the triumphs and tragedies of the worlds first computer. New York: Berkley Books.

Change is the only constant, so individuals, institutions, and businesses must be Built to Adapt. At Pivotal, we believe change should be expected, embraced, and incorporated continuously through development and innovation, because good software is never finished.

Refrigerator Ladies: The First Computer Programmers was originally published in Built to Adapt on Medium, where people are continuing the conversation by highlighting and responding to this story.

About the Author

Liz Huang

Liz Huang is the Head of Editorial at Pivotal.

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