Atomic Heritage Foundation

In partnership with the National Museum of Nuclear Science & History National Museum of Nuclear Science & History



Early IBM calculating machines at Los Alamos

The Computer Era

A MANIAC coding operator

Human Computers

Letter from John von Neumann to J. Robert Oppenheimer about purchasing IBMs for Los Alamos

Women vs. IBMs

John von Neumann, Richard Feynman, and Stanislaus Ulam at Los Alamos

John von Neumann

Paul Stein and Nick Metropolis playing modified chess with the MANIAC I


Punch card

Punch Cards

  • The Computer Era

    The Computer Era

    Manhattan Project physicist Julius Tabin on how the differences between the “computers” of World War II and today.

    Narrator: Manhattan Project physicist Julius Tabin describes how computers have changed since World War II.

    Julius Tabin: Things that are available now, we were just thinking about in those days. Doing some of the calculations for some of the weaponry, they needed mathematics and they needed to do arithmetic very fast. In those days, all we had was a Marchant calculator, and some mechanical calculators with gears and wheels that operated very slowly.

    I remember the first computer was in a room several times the size of this room, filled with vacuum tubes, etc., to make simple calculations. Now, if you remember the first early hand computers to do arithmetic, just did addition, division, etc., cost $500 or something for a thing which you can buy for $5 today. 

  • Human Computers

    Human Computers

    Los Alamos National Laboratory physicist James L. Smith discusses how the word “computer” has changed since World War II. Manhattan Project veterans Jean Bacher and Kay Manley recall working as “human computers” at Los Alamos during the Manhattan Project.

    Narrator: Los Alamos National Laboratory physicist James L. Smith explains how the definition of the word “computer” has changed since the 1940s.

    Jim Smith: The word “computer” didn’t exist then. They had women doing calculations with hand machines during the Manhattan Project. They also got the first things from IBM.

    But these weren’t really computing. They were sorting and doing rather simple things, and there was nothing in the sense of a modern computer. But those women doing those calculations, they called them “computers.”

    Narrator: Jean Bacher, Mici Teller, and Kay Manley, wives of leading Manhattan Project physicists, all worked as “computers.” Jean Bacher recalls her wartime work at Los Alamos.

    Jean Bacher: I was a computer. Mici Teller was working with me. We would divide up whether we worked in the morning or the afternoon.

    Narrator: Kay Manley describes how she used Marchant machines to perform complex calculations at Los Alamos during the war.

    Kay Manley: I worked in one of the statistician’s groups doing calculating on one of those big old Marchant machines, which you probably have no idea ever existed. They were the forerunners of the whole computing idea. They were big, they were clumsy, they were slow, and they made a tremendous amount of clatter. And of course, also, they were always breaking down.

    But we did a tremendous number of calculations on them. And of course, the calculations were very involved, some of them running to 10 and 12 figures. So that it meant you had to be very careful about punching the right figures and so on.

    I knew it was connected with the war and that if possible, to make it work, it would probably end the war quickly. That was as far as my knowledge went. I knew there was a great deal of mathematics involved, tremendous amount of mathematics involved.

    A good deal of my own particular calculating problems were done for Bob Serber, who was a very well-known theoretical person, who was there at Los Alamos. But that’s as far as I went, and I didn’t ask any questions. 

  • Women vs. IBMs

    Women vs IBMs

    Physicist Nicholas Metropolis recalls how Richard Feynman pit the women “computers” against the IBM machines to see who was faster.

    Narrator: Physicist Nicholas Metropolis recalls how Richard Feynman would pit the women “computers” against the IBM machines to see who was faster.

    Nicholas Metropolis: When the IBMs came along, they were all individual machines and we converted them into doing a lot of problems.

    Feynman's idea was to try to get a list of gals to do the comparison with the machines. This was, in a sense, a continuation of reliability theory.

    At first, the gals were winning. But then, they began to tire a little bit as the day wore on. Then the machines caught up with them and passed them.

    Narrator: Eventually, of course, it was no contest. Because the women went home for the day, while the computers worked on.

    Metropolis: When they stopped, the machines then were able to make progress in a great way.

  • John von Neumann

    John von Neumann

    Manhattan Project mathematician Peter Lax praises John von Neumann’s brilliant mind and impact on computing.

    Narrator: Manhattan Project mathematician Peter Lax explains John von Neumann’s influence on the history of computing.

    Peter Lax: Von Neumann was very deeply involved in Los Alamos. He realized that computers would be needed to carry out the calculations needed. Of course, he realized that computing would be important for every highly technical project.

    He was the most remarkable man. I am always utterly surprised how come he’s almost totally unknown. It is a name that should be known to every American—in fact, every person in the world, just as the name of [Albert] Einstein is.

    All people who had met him and interacted with him realized that his brain was more powerful than anyone’s they have ever encountered. I remember Hans Bethe even said—only half in jest—that von Neumann’s brain was a new development of the human brain. Only a slight exaggeration.



    Manhattan Project physicist Nicholas Metropolis built the MANIAC I computer at Los Alamos, basing it on computer architecture John von Neumann had developed at Princeton. Metropolis explains why he called it the “MANIAC.”

    Manhattan Project physicist Nicholas Metropolis built the MANIAC I computer at Los Alamos, basing it on computer architecture John von Neumann had developed at Princeton. Metropolis explains why he called it the “MANIAC.”

    Narrator: Nicholas Metropolis built the MANIAC computer at Los Alamos in the 1950s, using computer architecture developed by John von Neumann at Princeton. The acronym 'MANIAC' officially stood for "Mathematical Analyzer, Numerator, Integrator, and Computer," but, as Metropolis explains, it was also given more personal meaning.

    Nicholas Metropolis: I had returned to Los Alamos to try to do some of the organizing of the projects here, and spent the year in Princeton learning about the machine there that Johnny was building. That was the project that was going on at Princeton.

    I had proposed that it be called the MANIAC, and Johnny thought that that was too frivolous. But I had in mind calling it the MANIAC, because it would put an end to the naming of machines. It would not be allowed to pass. Because [but] it had just the opposite effect.

    So George Gamow, the astrophysicist, said that “Metropolis and Neumann Invent Awful Contraption.” But actually, the word “MANIAC” came ahead of what it stood for. 

  • Punch Cards

    Punch Cards

    Manhattan Project veteran Stanley Hall recalls using punch cards to program early computers at Los Alamos after World War II.

    Narrator: Manhattan Project veteran Stanley Hall worked as a laboratory technician in the computing division at Los Alamos National Laboratory after the war. As Hall describes, computers have come a long way since the days of punch cards. Early digital computers relied on punch cards, which used punched holes for data input or programming.

    Stanley Hall: I learned how to compute using the FORTRAN language. We had to have punch cards, in a tray like this. Just one card out of place, the code wouldn’t work. You’d have to go about four or five and line up the time that night, so the night crew would put your cards in. Then in the morning, you’d get the results.

    If you ever complained about the work they were doing—like they didn’t run your cards the way they were supposed to—mysteriously the next week, your cards would be dumped on the floor. You learned to not complain.

    I think with the fast computers you have now, you’d do things now that you wouldn’t even think of doing back then. There wouldn’t be room in the house for all the cards. 

Quick Fact:
The development of early computing benefited enormously from the Manhattan Project, especially with the Los Alamos laboratory’s developments in the field both during and after the war.