Hitting the Books: The women who made ENIAC more than a weapon

After Mary Sears and her team had revolutionized the field of oceanography, but before Katherine G. Johnson, Dorothy Vaughan and Mary Jackson helped put John Glenn into orbit, a cadre of women programmers working for the US government faced an impossible task: train ENIAC, the world's first modern computer, to do more than quickly calculate artillery trajectories. Though successful — and without the aid of a guide or manual no less — their names and deeds were lost to the annals of history, until author Kathy Kleiman, through a Herculean research effort of her own, brought their stories to light in Proving Ground: The Untold Story of the Six Women Who Programmed the World’s First Modern Computer.

Excerpted from the book Proving Ground: The Untold Story of the Six Women Who Programmed the World’s First Modern Computer by Kathy Kleiman. Copyright © 2022 by First Byte Productions, LLC. Reprinted with permission of Grand Central Publishing. All rights reserved.

Demonstration Day, February 15, 1946

The Moore School stood ready as people began to arrive by train and trolley. John and Pres, as well as the engineers and deans and professors of the university, wore their best suits and Army officers were in dress uniform with their medals gleaming. The six women wore their best professional skirt suits and dresses.

Kay and Fran manned the front door of the Moore School. As the scientists and technologists arrived, some from as far as Boston, the two women welcomed them warmly. They asked everyone to hang up their heavy winter coats on the portable coat racks that Moore School staff had left nearby. Then they directed them down the hall and around the corner to the ENIAC room.

Just before 11:00 a.m., Fran and Kay ran back to be in the ENIAC room when the demonstration began.

As they slid into the back of the room, everything was at the ready. At the front of the great ENIAC U, there was space for some speakers, a few rows of chairs, and plenty of standing room for invited guests and ENIAC team members. Across the room, Marlyn, Betty, and Jean stood in the back and the women smiled to each other. Their big moment was about to begin. Ruth stayed outside, pointing late arrivals in the right direction.

The room was packed and was filled with an air of anticipation and wonder as people saw ENIAC for the first time.

Demonstration Day started with a few introductions. Major General Barnes started with the BRL officers and Moore School deans and then presented John and Pres as the co-inventors. Then Arthur came to the front of the room and introduced himself as the master of ceremonies for the ENIAC events. He would run five programs, all using the remote control box he held in his hand.

The first program was an addition. Arthur hit one of the but-tons and the ENIAC whirled to life. Then he ran a multiplication. His expert audience knew that ENIAC was calculating it many times faster than any other machine in the world. Then he ran the table of squares and cubes, and then sines and cosines. So far, Demonstration Day was the same as the one two weeks earlier, and for this sophisticated audience, the presentation was pretty boring.

But Arthur was just getting started and the drama was about to begin. He told them that now he would run a ballistics trajectory three times on ENIAC.

He pushed the button and ran it once. The trajectory “ran beautifully,” Betty remembered. Then Arthur ran it again, a version of the trajectory without the punched cards printing, and it ran much faster. Punched cards actually slowed things down a little bit.

Then Arthur pointed everyone to the grids of tiny lights at the top of the accumulators and urged his attendees to look closely at them in the moments to come. He nodded to Pres, who stood against the wall, and suddenly Pres turned off the lights. In the black room, only a few small status lights were lit on the units of ENIAC. Everything else was in darkness.

With a click of the button, Arthur brought the ENIAC to life. For a dazzling twenty seconds, the ENIAC lit up. Those watching the accumulators closely saw the 100 tiny lights twinkle as they moved in a flash, first going up as the missile ascended to the sky, and then going down as it sped back to earth, the lights forever changing and twinkling. Those twenty seconds seemed at once an eternity and instantaneous.

Then the ENIAC finished, and darkness filled the room again. Arthur and Pres waited a moment, and then Pres turned on the lights and Arthur announced dramatically that ENIAC had just completed a trajectory faster than it would take a missile to leave the muzzle of artillery and hit its target. “Everybody gasped.”

Less than twenty seconds. This audience of scientists, technologists, engineers, and mathematicians knew how many hours it took to calculate a differential calculus equation by hand. They knew that ENIAC had calculated the work of a week in fewer than two dozen seconds. They knew the world had changed.

Climax complete, everyone in the room was beaming. The Army officers knew their risk had paid off. The ENIAC engineers knew their hardware was a success. The Moore School deans knew they no longer had to be worried about being embarrassed. And the ENIAC Programmers knew that their trajectory had worked perfectly. Years of work, effort, ingenuity, and creativity had come together in twenty seconds of pure innovation.

Some would later call this moment the birth of the “Electronic Computing Revolution.” Others would soon call it the birth of the Information Age. After those precious twenty seconds, no one would give a second look to the great Mark I electromechanical computer or the differential analyzer. After Demonstration Day, the country was on a clear path to general- purpose, programmable, all- electronic computing. There was no other direction. There was no other future. John, Pres, Herman, and some of the engineers fielded questions from the guests, and then the formal session finished. But no one wanted to leave. Attendees surrounded John and Pres, Arthur and Harold.

The women circulated. They had taken turns running punched cards through the tabulator and had stacks of trajectory printouts to share. They divided up the sheets and moved around the room to hand them out. Attendees were happy to receive a trajectory, a souvenir of the great moment they had just witnessed.

But no attendee congratulated the women. Because no guest knew what they had done. In the midst of the announcements and the introductions of Army officers, Moore School deans, and ENIAC inventors, the Programmers had been left out. “None of us girls were ever introduced as any part of it” that day, Kay noted later.

Since no one had thought to name the six young women who programmed the ballistics trajectory, the audience did not know of their work: thousands of hours spent learning the units of ENIAC, studying its “direct programming” method, breaking down the ballistics trajectory into discrete steps, writing the detailed pedaling sheets for the trajectory program, setting up their program on ENIAC, and learning ENIAC “down to a vacuum tube.” Later, Jean said, they “did receive a lot of compliments” from the ENIAC team, but at that moment they were unknown to the guests in the room.

And at that moment, it did not matter. They cared about the success of ENIAC and their team, and they knew they had played a role, a critical role, in the success of the day. This was a day that would go down in history, and they had been there and played an invaluable part.