During WWII, a top-secret project to build the first programmable digital computer was underway at the University of Pennsylvania. The U.S. Army was looking for a faster way to run complicated ballistic trajectory calculations which, at the time, took a group of women mathematicians 30-40 hours to complete. The Electronic Numerical Integrator and Computer, “ENIAC,” was 8ft by 80ft and comprised of 40 black steel switches, vacuum tubes and wires. Physicists John Mauchly and Presper Eckert, who created ENIAC, needed someone to figure out how to program the machine – they asked six women.

Kathleen McNulty, Frances Bilas, Frances Elizabeth Synder, Marlyn Wescoff, Ruth Lichterman and Betty Jean Jennings had no instruction manual and at first weren’t even allowed to be in the same room as the classified computer. But still, the world’s first programmers figured out how to work the behemoth, reducing calculations that had taken a week to just 20 seconds, and spurring beginning of a technological revolution.

The contributions of these women aren’t widely known, but KATHY KLEIMAN has made it her mission to share their stories and their pioneering work in the field of computing. She founded the ENIAC Programmer Project and her new book is Proving Ground: The Untold Story of the Six Women Who Programmed the World’s First Modern Computer.