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EDVAC First Draft Report – The von Neumann architecture – 1945 A.D.

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EDVAC First Draft Report

John Mauchly (1907–1980), J. Presper Eckert (1919–1995), John von Neumann (1903–1957), Herman Goldstine (1913–2004)

“Before ENIAC was even operational, J. Presper Eckert and John Mauchly were already designing an even more powerful computer, the EDVAC (Electronic Discrete Variable Automatic Computer).

Whereas ENIAC’s architecture could be thought of as 20 automatic adding machines wired together, EDVAC resembled what we’ve come to think of as a modern computer. It had a memory bank that stored both the computer’s program and data, and a central processing unit (CPU) fetched instructions from memory and executed them. The program stored in the main memory directed when data should be copied from memory into the CPU, when mathematical functions were applied, and when the results should be written back to main memory.

Today we call this the von Neumann architecture after John von Neumann, the Hungarian-born polymath who immigrated to the US in 1930 and was one of the first faculty members of the Institute for Advanced Study in Princeton, New Jersey, along with Albert Einstein and Kurt Gödel.

Von Neumann and fellow physicists designed the explosive lenses used to detonate the implosion bombs used at Trinity, New Mexico, and Nagasaki and Hiroshima, Japan. While working on those tremendously intricate computations, von Neumann had a chance meeting at a train station with Herman Goldstine, a mathematician who was the Army’s liaison with Eckert and Mauchly at the University of Pennsylvania. Goldstine introduced von Neumann to Eckert and Mauchly; soon thereafter, von Neumann joined the study group that was designing the EDVAC.

Von Neumann wrote up his notes while commuting to Los Alamos, New Mexico, and mailed them back to Goldstine, who typed them up, titled the document First Draft of a Report on the EDVAC, put von Neumann’s name on the cover (even though most of the work was that of Eckert and Mauchly), and distributed 24 copies.

Even though modern computers have an architecture that is closer to the machines developed by Howard Aiken—the so-called Harvard architecture—the phrase “von Neumann architecture” is still widely used to describe modern computers.”


“EDVAC exhibit at the Franklin Institute. The square sign reads: “Pilot Model EDVAC Electronic Discrete Variable Computer Designed and Built by Moore School of Electrical Engineering, University of Pennsylvania, for Ordnance Department, U.S. Army.””

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