What is the Von Neumann architecture?

The von Neumann architecture is a computer design based on a 1945 report by John von Neumann detailing a stored-program computer. It uses a single shared memory and common bus for both instructions and data, leading to the well-known von Neumann bottleneck where instruction fetches and data operations cannot happen simultaneously. Although widely attributed to von Neumann, the core design was actually created by John Mauchly and J. Presper Eckert.

What we know

• The von Neumann architecture uses a common memory and address space for both instructions and data. [1, 2]
• The design originates from the 1945 First Draft of a Report on the EDVAC, written by John von Neumann, though the core ideas were designed by John Mauchly and J. Presper Eckert. [2]
• Sharing a common bus prevents data operations and instruction fetches from occurring at the exact same time, creating a limitation known as the von Neumann bottleneck. [2]
• Stored-program computers represented a major advancement over earlier machines like the ENIAC, which required manual reconfiguration using plugboard wiring and switches. [2]

Still open

• Historians note that attributing the invention of the architecture solely to John von Neumann is historically incorrect, as Eckert and Mauchly had essentially finished the design beforehand.

Where to go next

• compared withHow does the Harvard architecture differ?
• what followedWhat is the von Neumann bottleneck?
• whoWho were John Mauchly and J. Presper Eckert?
• a case in pointWhat was the EDVAC computer?
• the bigger pictureWhat is a stored-program computer?
• an unexpected connectionHow do modern processors bypass the von Neumann bottleneck?Even though modern computers appear to use a standard von Neumann main memory setup, they actually utilize separate internal CPU caches for instructions and data to circumvent memory bottleneck limitations.

Sources

• [1]von Neumann architecture (Wikidata Q189088) · CC0 1.0
• [2]Von Neumann architecture · CC BY-SA 4.0
• [3]Harvard architecture · CC BY-SA 4.0
• [4]Modified Harvard architecture · CC BY-SA 4.0
• [5]Von Neumann · CC BY-SA 4.0