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The recent passing of computing pioneer David Caminer reminds me of Leo Fantl, one of Caminer’s original team of programmers, also deceased. Leo Fantl, b. August 8, 1924, Teptliz Schoenau, Czechoslovakia – November 11, 2000, Johannesburg, Africa.

Leo hired me to be a salesman at LEO Computer Bureau in Johannesburg, South Africa, in the late seventies. I wanted to be a trainee computer operator/programmer but they thought I was presentable and insightful about solving business problems so they put my enthusiasm to work in sales. I did surprisingly well, making salesman of the month several times over in my novice year, but I had no passion for selling. I wanted to control the machine.

The Brits took an early lead in business computing which, in several key ways, was quite different to the mathematical machines being pioneered in the US. Math required lengthy calculations on a small data set, usually with an equally small output (e.g. calculating trajectories or chain reactions). Business computing required simple, repetitive calculations on a large amount of input data, generating an equally large amount of output data (e.g. payroll or invoicing). This meant that business computers had to develop ways to quickly store and input lots of of data, keep more of it in core memory and also output much more. Long glass tubes of mercury were developed as delay lines in which data could be stored and refreshed until required, making up the core memory, and paper tape was used to input and output data.


The Lyons Tea Houses sponsored the development of such a machine at Cambridge University on the agreement that they could replicate the working machine at their offices. The office was called the Lyons Electronic Office, or L.E.O.. Leo Fantl was one of the first to program the machine and pioneered PAYE tax calculations in large payroll systems. The coincidence between Leo’s first name and L.E.O., the electronic office, was just that.

Leo Fantl went to Johannesburg to install a LEO Computer for payroll systems at the Rand Mines. He was recently widowed, fell in love with the country and found more business for the company so he stayed on, creating the LEO Computer Bureau which eventually employed me.

I recall Leo very fondly. He was a workaholic leader, sleeves always rolled up, his door always wide open and in spite of having a business to run, he was always in the thick of operations and development.

Suggested reading: A Computer called LEO by Georgina Ferry | Yahoo group “Leo Computers” | Leo Fantl biography | L.E.O.: The Incredible Story of the World’s First Business Computer | Douglas Martin’s article “David Caminer, a Pioneer in Computers, Dies at 92” in The New York Times | The Register’s article Blighty’s revolutionary Cold War teashop computer – and Nigella Lawson | An electronic history of J.Lyons & Co. | Leo Computer Society | Leo: First Business Computer by Peter John Bird


  1. Harry, I found your page by accident – Leo were really good days. I am still in contact with Neil Hymers, Mike Stowe etc. A great page and a wonderful tribute to Leo Fantl. Kind regards, Colin Ansell

    • Hey Colin, thanks for dropping in here (albeit by accident)! I’m still exploiting my passion for “controlling the machine”, building publishing systems, working at The New York Times — directing people, more so than hands-on these days. But it amazes me how old technologies like the IBM 360 mainframe’s hypervisor/vmm layer are at the core of modern ideas like cloud computing and virtualization. I enjoy the future of computing as much as I appreciate its past. Regards, Harry

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