Six Women Programmed the First Modern Computer and Weren't Invited to the Demo's Dinner

When ENIAC was formally dedicated at the Moore School of Electrical Engineering in Philadelphia on February 15, 1946, the demonstration program calculated the trajectory of an artillery shell in 15 seconds — about a thousand times faster than the electromechanical calculators it was meant to replace. The speech-makers thanked John Mauchly, J. Presper Eckert, and the U.S. Army. They did not thank the people who had written the program.

Those people were six mathematicians: Jean Jennings, Betty Snyder, Frances Bilas, Marlyn Wescoff, Ruth Lichterman, and Kay McNulty. The Army had hired them, in part because the men with appropriate math degrees were at war, and given them the manuals to a machine they were not allowed into the room of for security reasons. They worked from the wiring diagrams and pencil-and-paper. By 1946, they could program ENIAC by sliding cables and rotary switches across its 40 panels — a process that involved physically rewiring the machine for each new problem. Penn classified them as "subprofessionals" while their male peers, holding the same degrees, were called "professionals."

None of the six were invited to the formal dinner that evening. Snyder and Jennings, who had built the trajectory demo, watched as the credit went elsewhere; an early newspaper photograph of the dedication captioned them as "refrigerator ladies" — models posing with the equipment. They went on to design programs for UNIVAC and to invent some of the first programming techniques still used today. The historian Kathryn Kleiman started tracking them down in the 1980s for a documentary project. In 1997 the surviving four were inducted into the Women in Technology International Hall of Fame.