EDVAC

EDVAC (Electronic Discrete Variable Automatic Computer) was an early electronic computer developed in the United States during the 1940s. It is one of the first practical stored-program computers and helped popularize the architecture later known as the von Neumann architecture. The project built on work associated with John von Neumann and the team at the Moore School of Electrical Engineering, including J. Presper Eckert and John Mauchly. Von Neumann’s 1945 First Draft of a Report on the EDVAC outlined a design in which program instructions and data are stored in a single read/write memory, a concept that became central to subsequent computer design.

Design and features of EDVAC emphasized binary arithmetic, a fixed word length, and a stored-program approach. The machine used a word length of 44 bits and memory of about 1,000 words, implemented with mercury delay line technology. Its central processing unit included an accumulator and a multiplier unit, and it supported a basic set of operations for arithmetic, data manipulation, and control flow. Input and output were provided by devices such as paper tape readers and printers, enabling interaction with external data.

Development and deployment proceeded over the late 1940s, with construction carried out by the Moore School team. After technical and organizational delays, EDVAC was completed and installed at the U.S. Army’s Ballistic Research Laboratory at Aberdeen Proving Ground in Maryland, becoming operational in 1951. The machine demonstrated the viability of stored-program operation and binary processing, influencing the design of later computers and reinforcing the concept that program instructions could reside in memory alongside data.

Legacy of EDVAC lies in its formalization of the stored-program approach and its impact on the development of early computer architectures. It is frequently cited as a foundational step in the transition from special-purpose machines to general-purpose, programmable computers.

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