# John von Neumann: From the Manhattan Project to the Princeton Architecture

## John von Neumann has revolutionized the world of computing through his work on the Manhattan Project, the von Neumann (Princeton) Architecture, and the first IAS computer.

Before electrical engineers were doing the inventing and designing, many mathematicians were paving the way into uncharted territories. A shining example of this is the works and life of John von Neumann.

*John von Neumann. Image used courtesy of Alan W. Richards and Brittanica*

John von Neumann was born on December 28, 1903, in Budapest, Hungary. From a young age, von Neumann was a prodigy because of his advanced ability to compute large equations and memorize extensive lists of numbers. Despite his mathematic abilities, he got his first degree in chemical engineering, though he later returned to his love of mathematics when he got his doctoral degree in 1928.

Eventually, during a politically-stressful time in Europe, von Neumann received an invitation from Princeton to visit, which led to his lifelong role as one of the first six founding professors for the Institute for Advanced Studies (IAS) mathematics.

### Work on the Manhattan Project

During WWII, von Neumann was one of the chosen few to work on the Manhattan Project, specifically at Los Alamos. His role on the project was to calculate the explosive shockwaves for the Fat Man atomic bomb. To conduct those calculations, he utilized a specialized IBM mechanical tabulating machine.

*Early IBM calculating machines that were used at Los Alamos. Image used courtesy of the Atomic Heritage Foundation*

Using the IBM machine, von Neumann worked on the atomic bomb implosion design from Seth Neddermeyer. Neddermeyer's design required a hollow sphere that included fissionable plutonium that could implode symmetrically. This symmetry was necessary to get the plutonium into a critical mass at the center.

*An image of John von Neumann (left) and Robert Oppenheimer (right) in front of the IAS machine. Image used courtesy of Alan W Richards and CHM*

At this time, computers tended to be mostly human-powered with humans doing most of the tedious calculations on a mechanical calculator, which usually broke down after extensive use. This issue caused von Neumann to consider the use of mechanical devices that could handle more general computations and led him to design an architecture for such a device––later becoming the von Neuman (or Princeton) architecture.

### Von Neumann (Princeton) Architecture

After the war, when von Neumann was creating his computer architecture, he was inspired by the relationship between a computer and the brain, namely the language of mathematics and the nervous system. This way of thinking lead to the concept of the von Neumann architecture including memory, a CPU, and I/O interfaces.

*A diagram of the von Neumann architecture. Image used courtesy of NC Lab*

von Neumann's work with computing was largely reliant on Alan Turing, another mathematician at Princeton. Though von Neumann wanted to create the first computer, the invention of the ENIAC (Electronic Numerical Integrator and Computer) had already occurred.

Undeterred, von Neumann went on to create the first IAS computer, which was based on his architecture. von Neumann decided that one major feature of the IAS computer was that future advances were to be public domain. Since this innovation was open to the public, it spurred momentum for creating computers and building upon the original creation.

### The von Neumann Bottleneck

Though revolutionary at the time, the von Neumann architecture has its faults. The von Neuman Bottleneck (VNB) is when a computing system doesn't have an adequate data transfer rate between the CPU and memory. This bottleneck occurs because the CPU must idle while the system is accessing the memory. A way to overcome this effect is to integrate memory and data into a single unit, thus allowing the data to be store and utilized at the same time.

*Computer architectures with (a) a von Neumann structure and (b) a non-von Neumann structure. Image used courtesy of Qiao-Feng Ou, et al.*

Though John von Neumann's work is growing out of use in some applications, there is no doubt that his contributions to engineering have helped bring computing where it is today.

### See News Relating to the von Neumann Architecture

To learn more about von Neumann's architecture and its effects on current designs, check out the following articles:

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