The Men Who Built the 'Giant Brain'
In the midst of World War II, the U.S. Army had a pressing problem: calculating artillery firing tables was a slow, laborious process done by hand. At the University of Pennsylvania's Moore School of Electrical Engineering, two men proposed a radical
solution. Physicist John Mauchly and engineer J. Presper Eckert envisioned an electronic machine that could perform calculations at speeds never before imagined. Their government-funded project, codenamed "Project PX," resulted in the Electronic Numerical Integrator and Computer, or ENIAC. Unveiled in February 1946, the machine was a marvel, weighing 30 tons and filled with nearly 18,000 vacuum tubes. It could complete a complex trajectory calculation in 20 seconds, a task that took a human 40 hours. Mauchly and Eckert were hailed as the fathers of modern computing, the brilliant inventors of the hardware that changed the world.
Before Machines, 'Computers' Were Women
Before ENIAC gave the word "computer" its modern meaning, the term was a job title. A computer was a person, almost always a woman, who performed complex mathematical calculations by hand. During the war, the Army recruited hundreds of women with mathematics degrees for this critical task. This was seen as tedious, sub-professional work, not fit for male engineers who were busy with more prestigious hardware projects. It was from this pool of brilliant human "computers" that the Army selected a small group for a top-secret assignment: to make the new ENIAC machine actually work. This distinction between building the machine and operating it would become the fault line where history was written and then rewritten.
The Six Women Who Programmed ENIAC
The six women chosen were Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas, and Ruth Lichterman. They were given blueprints of the massive machine but, at first, no security clearance to see it. With no programming languages or even an instruction manual to guide them, they had to invent the discipline of software programming from scratch. Their job wasn't simply to flip switches; they had to understand the machine’s architecture on a fundamental level, break down complex differential equations into steps the machine could execute, and then physically wire the program using a labyrinth of cables and switches. They became the world's first digital programmers, developing techniques like subroutines that are still foundational to coding today. They crawled inside the machine to find and replace faulty vacuum tubes, effectively debugging the world's first supercomputer.
The Decision to Erase Them
The "hidden decision" was not a formal, documented order but a deeply ingrained cultural one. When the ENIAC was revealed to the public and the press in 1946, the Army and the university presented the machine as the sole hero of the story. Mauchly and Eckert were celebrated, but the six women who made the machine perform its miracles were not even introduced. They weren't invited to the celebratory dinner that followed the press conference. In the iconic photographs from the launch, the women are present, often standing before the vast panels of switches and cables. For decades, however, computer historians and journalists assumed they were merely models—often called "refrigerator ladies"—posing to add scale and glamour to the hardware. Their intellectual labor was deemed clerical and, therefore, invisible and unimportant. The decision was to celebrate the invention of the hardware, while completely ignoring the equally innovative creation of the software.
A Legacy of Invisibility
The erasure of the ENIAC Six had profound and lasting consequences. It helped solidify the myth that computing genius was an exclusively male domain, centered on building machines rather than programming them. As the field of computing professionalized, hardware was seen as the prestigious and difficult work, while software—the work pioneered by women—was initially considered a lower-status, less-skilled task. This perception contributed to a gendered divide in technology that persists to this day. For nearly 50 years, the story of the ENIAC programmers was lost. It wasn't until the 1990s, thanks to the research of people like Kathy Kleiman, that their names and contributions were rediscovered and they began to receive their due, including induction into the Women in Technology International Hall of Fame in 1997. Their story is a powerful reminder that innovation is rarely the product of a few lone geniuses, but of collaborative effort—and that a decision about who gets the credit can shape an entire industry's identity.
