Last summer, when I was visiting NCAR, Warren Washington gave me some papers to read on the first successful numerical weather prediction, done on ENIAC in 1950, by a team of meteorologists put together by John von Neumann. von Neumann was very keen to explore new applications for ENIAC, and saw numerical weather prediction as an obvious thing to try, especially as he’d been working with atmospheric simulations for modeling nuclear weapons explosions. There was, of course, a military angle to this – the cold war was just getting going, and weather control was posited as a potentially powerful new weapon. Certainly that was enough to get the army to fund the project.

The original forecast took about 24 hours to compute (including time for loading the punched cards), for a 24-hour forecast. This was remarkable, as it meant that with a faster machine, useful weather prediction was possible. There’s a very nice account of the ENIAC computations in:

…and a slightly more technical account, with details of the algorithm in:

So having read up on this, I thought it would be interesting to attempt to re-create the program in a modern programming language, as an exercise in modeling, and as way of better understanding this historic milestone. At which point Warren pointed out to me that it’s already been done, by Peter Lynch at University College Dublin:

And not only that, but Peter then went one better, and re-implemented it again on a mobile phone, as a demonstration of how far Moore’s law has brought us. And he calls it PHONIAC . It took less than a second to compute on PHONIAC (remember, the original computation needed a room-sized machine, a bunch of operators, and 24 hours).


  1. And if people visit the Computer History Museum in Mountain View, CA, we have a piece of the ENIAC on display.

  2. @John: I’ll be sure to visit when I’m next in the Bay Area. I managed to visit the National Computer Museum in Bletchley Park in the UK last summer, where they have a rebuild of the Colossus on display, touted as the first programmable electronic computer (they also claim the Manchester machine as the first stored program computer). It’s amusing to see a healthy rivalry between the UK and the US about which machine counts as the first real computer…

  3. Don’t forget EDSAC. There are, oddly enough, exactly as many prizes as there are rivals. How’d that happen?
    I think the prize which makes most sense to me is for the first computer with the program stored in main memory. For this, Manchester’s Baby wins, or Cambridge’s EDSAC if one requires some minimum level of utility.

  4. I went to the Computer History Museum a few years back and it was quite disconcerting to see a VAX 11/780 there – one of the machines I cut my programming teeth on. I’m used to seeing ancient implements in museums (stone axes and so forth) but to see something I used and knew very well in a *museum* – made me feel old!

  5. re: VAX … that’s a recent machine, not an old one.

    The Museum has a 25,00-sq-ft professional-grade exhibition that just opened, thanks to $$ from Bill&Melinda Gates, Intel and others. We go much further back: one of the world’s 2 Babbage Engines, usually cranked once a day, by specially-trained crankers.

    We have keypunches, and even a working IBM 1401 computer room, as well as a PDP-1 on which we demonstrate the original SpaceWar once in a while.

    A few years ago, I took a gang of first-term Stanford freshman in the accelerated computer science program. [Stanford CS department is very highly ranked.] Of course, all of them had programmed in C++ for years, built own Linux machines, had often learned to type on PC before they could write, grew up with PCs in the house, etc.

    But they had never seen a keypunch:
    Q: What did people do with that?
    A: That’s how we wrote code?
    Q: No way! Nobody would code that way!! (muttering, they actually used this junk)
    A: Wait till you see paper tape.

    On the other hand, at a Fellows dinner one time, our guests included Gene Amdahl and Arno Penzias, and Arno hadn’t seen the Museum before so I took them around, and their conversation was different, with reminiscences of components from the 1950s.

    Finally, in “who was first” sweepstakes, don’t forget Konrad Zuse. We have part of one his systems as well.

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