When the Electronic Numerical Integrator and Computer (ENIAC) was unveiled in 1946, it represented a technological revolution. Built at the University of Pennsylvania’s Moore School of Electrical Engineering, ENIAC was the first general-purpose electronic computer — an immense machine of 18,000 vacuum tubes that could perform calculations faster than any device before it. But behind its success stood six remarkable women whose expertise and innovation brought the machine to life. Kathleen McNulty Mauchly Antonelli, Jean Jennings Bartik, Frances Elizabeth Snyder Holberton, Marlyn Wescoff Meltzer, Frances Bilas Spence and Ruth Lichterman Teitelbaum were the first programmers in computing history, laying the groundwork for modern software and systems design.
From Human “Computers” to Pioneers
During World War II, the U.S. Army employed hundreds of women as “computers” to calculate ballistic trajectories by hand for artillery weapons. Many of these women worked at the Moore School of Engineering, where researchers were developing faster electronic methods to handle these demanding calculations. Among them were six women who would soon be chosen to program the newly built ENIAC. Trained in mathematics but with no programming precedent to follow, they had to interpret complex wiring diagrams and translate mathematical equations into a physical sequence of switches, cables and punch cards. Their ability to master the ENIAC’s intricate design made them the first generation of computer programmers.
Building the Brain of ENIAC
Programming the ENIAC was unlike anything that existed before. The women were responsible for configuring the machine’s 40 massive panels, manually connecting thousands of cables and setting hundreds of switches for each problem. They worked directly with inventors John Presper Eckert and John Mauchly, learning every circuit and operation in the 30-ton computer. ENIAC could complete in seconds calculations that once took hours or even days by hand. The women not only programmed ENIAC but also debugged its systems, identifying errors, creating repeatable subroutines and inventing early programming principles still in use today. Their expertise turned ENIAC from a static electronic device into a functioning, adaptive computing system.
Meet the ENIAC Six: The First Programmers
Each of the six women brought unique strengths to the project. Kathleen McNulty Mauchly Antonelli and Frances Bilas Spence, both graduates of Chestnut Hill College, were expert mathematicians who helped translate equations into machine processes. Jean Jennings Bartik, from Missouri, became co-lead programmer and later guided ENIAC’s transformation into a stored-program computer. Frances Elizabeth Snyder Holberton, a University of Pennsylvania graduate, developed early debugging methods and later contributed to the creation of COBOL and FORTRAN languages. Marlyn Wescoff Meltzer and Ruth Lichterman Teitelbaum conducted ENIAC’s first public demonstration in 1946, showcasing the machine’s unprecedented speed. Together, these women defined what programming would become: logical, precise and deeply creative.
Overlooked at First, Recognized Later
Despite their central role, the six women were largely omitted from public recognition when ENIAC was revealed. Media coverage focused on the male engineers, while the programmers’ contributions were dismissed as clerical work. For decades, their achievements remained obscured in archives and photographs. It wasn’t until the 1990s that historians and technologists began to restore their legacy. In 1997, the six were inducted into the Women in Technology International Hall of Fame. Later, Holberton and Bartik received the IEEE Computer Pioneer Award, acknowledging their fundamental role in computer science. Their story has since inspired books and documentaries, and it’s renewed awareness of women’s early contributions to computing.
The Legacy of the ENIAC Six
The ENIAC Six not only programmed the world’s first electronic computer, but they also established the principles of programming itself. Their techniques for sequencing commands, debugging and reusing code became the foundation for all future computer operations. ENIAC’s success also proved that large-scale electronic computing was possible, leading directly to systems like EDVAC, UNIVAC and eventually the personal computer. Today, fragments of ENIAC are displayed at the University of Pennsylvania and the Smithsonian Institution, standing as reminders of a breakthrough made possible by six brilliant women. Their story embodies the intersection of innovation and persistence that continues to define the evolution of technology.
Sources: Penn Engineering, IEEE Life Members, IEEE Spectrum, IEEE Computer Society
