Stored-Program Computer

A stored-program computer is a computer that keeps the instructions of the program it is running in the same fast electronic memory as its data, rather than reading them from an external device such as punched cards or a plugboard during operation. The idea traces back to Alan Turing's 1936 description of a theoretical universal computing machine, and the Manchester Baby is generally recognized as the first electronic computer to run a stored program, doing so on 21 June 1948; the modified ENIAC followed in April 1948 and EDSAC became operational in May 1949. Architectures differ in how memory is organized: a von Neumann architecture uses the same memory and access path for both instructions and data, while a Harvard architecture keeps them separate.