In 1945, 20-year-old mathematician Betty Jean Jennings moved to Philly and started work on a secret military project: the first modern electronic computer. Now, in a fascinating posthumous memoir, the tech pioneer tells her own story.
The first day of class, in walked this woman dressed in a skirt and blouse, with a cigarette dangling from the side of her mouth. She perched on the edge of her desk with her left leg thrown up over the corner and began to lecture in a Brooklyn accent. I sure knew I was in the big city now! The girls at Northwest Missouri State Teachers College had to go down to the school’s greenhouse to smoke a cigarette.
The classes lasted for about an hour a day for a couple of weeks. There were six or so of us in the class. I asked lots of questions, and Adele seemed to like that. She taught us about computing methods on calculators, such as how to do inverse interpolations.
My room at the YWCA was very small and plain with a bed and dresser. There was a toilet and showers down the hall. The room went for two dollars a night, but I could stay at the Y for only a week, so I needed to find permanent housing… I decided to go to the housing office on the Penn campus. They sent me to a Mrs. Furlong, who owned a house on Spruce Street, in a neighborhood of large, three-story houses with white cement steps that were kept spotless—a hallmark of the area. Mrs. Furlong rented rooms to students from the Curtis Institute of Music and a technology school. Her son-in-law was Mason Jones, the lead horn player in the Philadelphia Orchestra, one of the finest orchestras in the world. Her rooms had kitchen privileges. She had a room. I moved in.
I had a great time living with the students from Curtis. All the students were on full scholarship, and they were all extraordinary musicians. I was no competition for any of them, so they told me many things they would not have told another musician. I earned their trust by never gossiping about what I was told and trying to give them the best advice I could when asked.
Looking back, I hope I was a good listener and good friend to those who shared their fears and aspirations with me. You see, several of the boys talked to me about whether or not they were gay. Many believed at that time that artistic men tended to be more homosexual than businessmen or athletes. Some were and some weren’t, but all were anxious about what the future might hold for them. We also talked about how they felt about their music and they would take me to concerts at the Academy of Music. I have zero musical ability, so I was thrilled to be involved with such talented people. These young men from Curtis would eventually become the top musicians in orchestras around the country.
…The computing group was located in a beautiful old brick fraternity house on Thirty-Fourth and Walnut. There were very few men on campus, so it had become available. The group had originally been located in one of the houses around Penn but had moved to the frat house later to have more space. They told me they had meant for me to get a physical before I arrived, but since I was here I could go to a doctor around the corner. It was a Friday afternoon. The doctor examined me for a while and was overly familiar, then he said, “I don’t have time to finish this. You must come back on Monday afternoon.” I said, “Okay,” and left. Sunday afternoon, I got a call at the YWCA from the doctor saying that he would finish the physical if I would come to his home. I must say, the old farm boys had taught me well to stay out of secluded places such as haylofts with them. I considered that a man’s home on a Sunday afternoon qualified as secluded a place as a hayloft, so I declined, and kept my appointment on Monday afternoon. He was “handsy” at that follow-up. When I informed the manager of the project what kind of lecher he was using as a doctor, he was no longer recommended.
I was hired as a “computer” with a job rating of SP-6 (sub-professional 6). Men math majors were given professional ratings, but women were not given professional ratings until later—I got mine in 1946. As an SP-6, I made two thousand dollars a year, plus four hundred dollars a year for working Saturdays. The men made the same as we did for the same job, but there were only two or three men doing that job.
On the early days of programming the ENIAC, which was the world’s first stored-program computer:
I find it remarkable how many programming pioneers were women. For instance, Grace Hopper worked on the Mark I calculator at Harvard and developed the first compiler for a computer programming language. During World War II, women ran the code-breaking programs on the Colossus machines at Bletchley Park in England for Prime Minister Churchill’s secret intelligence group, which has been credited with shortening the war by eighteen months. These women were generally never named and were not allowed to tell anyone—not even family members—what they were doing during the war. Immediately following the war, American women programmed the Whirlwind at MIT, which was completed in 1951, the first computer to display real-time video.
When the other five ENIAC women and I answered an advertisement for female math majors, we stepped into the midst of this lineage. Our official job title was “computer”; no one thought of the title of “programmer” until well after the ENIAC was in operation. Initially all our job description called for us to do was to set switches and plug in cables to represent the problem being calculated. You see, originally, the designers and planners of the ENIAC thought that mathematicians would design the setup for their own problems, and we women would just set up the hardware of the ENIAC and run the problem. But it quickly became clear that planning the program setup was too complex for mathematicians to learn easily, and they had neither the time nor the inclination to do so. The Ballistics Research Lab at the Moore School proceeded to select six women to receive training to become ENIAC programmers starting in June 1945, and the ENIAC women became the programmers who designed the flowcharts and formats for planning the programs that ran on the ENIAC.
If the ENIAC’s administrators had known how crucial programming would be to the functioning of the electronic computer and how complex it would prove to be, they might have been more hesitant to give such an important role to women. I believe that Herman Goldstine was having difficulty with programming, and that is why he invited Betty and me to his apartment in West Philadelphia on February 2, 1946.
Herman asked Betty and me if our trajectory program was ready to run on the ENIAC. We told him that it was indeed ready to go. Goldstine then invited Betty and me to run the program on the ENIAC for the first public demonstration on February 15, 1946. As you can imagine, we were thrilled and delighted that our program would be the one to be demonstrated.
…The ENIAC was the first electronic computer built and demonstrated to the world. Computers like the Z3 in Germany and the Colossus in England had been built and run secretly during World War II, but nobody outside of a small circle had heard of them. All other predecessors of the ENIAC, such as Harvard’s Mark I and the Stibitz machine from Bell Laboratories, were electromechanical. The ENIAC opened the gateway to electronic computing, which eventually led to the computing industry we know today. It is hard to imagine, but the behemoth ENIAC had less computing power than a laptop or palm-held computer of today. It ran at 100 kilocycles (100,000 cycles per second), while today’s personal computers run at several gigahertz (billions of cycles per second)—more than 10,000 times as fast as the ENIAC. Yet only sixty years ago, such computing power was even more breathtaking than the computing speeds of PCs today.
The ENIAC’s forty panels, which almost covered the walls of its forty-by-thirty-foot room, contained the electronics and controls of the various units needed to do calculations: twenty accumulators (each of which could add or subtract a ten-decimal-digit number carrying a positive or negative sign), a multiplier, a divider/square-rooter, three function tables (each of which could store 102 twelve-decimal-digit numbers), a card reader, a card punch, a master programmer (the control unit for programs), a cycling unit, and power supplies.
The press hailed the ENIAC as a “giant brain,” and scientists from around the world came to see this marvel and learn whether it could help solve some of the millennium problems—ones that would take a thousand years to compute using a hand calculator—that plagued them.
On the ENIAC’s triumphant public unveiling—while the women who’d programmed it were promptly forgotten:
As the ENIAC made the calculations for the trajectory, its calculations were shown in the lights of the accumulators, which flickered and flashed as the numbers were built up and transferred from one accumulator to another and finally to the card punch to output the result. The tops of ENIAC’s neon bulbs were small and nothing spectacular to look at, which was unfortunate, since a movie crew would be there to film the ENIAC in action. Consequently, for several accumulators, Pres and John (the ENIAC’s inventors) placed halves of Ping-Pong balls over the tops of the neon bulbs and painted a large number on each one; the numbers denoted the row each vacuum tube represented (an integer from 0 to 9). The numbers showed up clearly, especially since the room’s lights were turned off for the demonstration, and the brightly lit, flashing “bulbs” gave viewers something dramatic to view.
The demonstration proved to be spectacular. As Pres had promised those in attendance, the ENIAC raced through the calculations of the shell’s arc faster than the time it took the shell to trace it. It was unheard of that a machine could reach such speeds of calculation, and everyone in the room, even the great mathematicians, were in complete wonder and awe at what they had just seen. The ENIAC used IBM punched cards to hold input and output data and for printing, so following the demonstration we—Betty and I and perhaps Kay—took the output punched cards to the IBM tabulator and printed them out as souvenirs for the attendees. The tabulator read the punched cards and printed the output on ordinary paper in ordinary language that described the trajectory calculation.
Some in that august assembly to whom we handed the printed output merely glanced at it and slipped it into their inside breast pocket; others studied it curiously, as if trying to fathom its mysteries. That seemingly ordinary piece of paper was a kind of Rosetta stone, providing the key not to the past, but to the future—a future so breathtakingly innovative that it has produced wondrous wireless, mobile communication devices and other technological achievements that in 1945 were either undreamed of or the stuff of science fictions…
After that exciting ENIAC demonstration, the men all went out to eat and celebrate together. However, the ENIAC women were left behind with barely a word of congratulations for our many contributions to the success of the project. The ENIAC female programmers had always felt respected and valued by our male coworkers. Yet that night we were forgotten, even by them. Why? I don’t have an adequate answer, other than to say that it was a different time and society at large expected us to stand behind our men and silently support them. Like every other American woman, the ENIAC women played the role society had assigned to us and we played it well and generally without rancor, although not without some hurt feelings.
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