Jay W. Forrester, born in 1918, American electrical engineer, management expert, and inventor of the random access magnetic-core memory for computers. This component of computer architecture evolved into random access memory (RAM), the central information storage device used in most computers.

Born in Anselmo, Nebraska, Forrester studied at the University of Nebraska and the Massachusetts Institute of Technology (MIT). After graduating in 1945 with a M.S. degree in electrical engineering, he remained at MIT to teach and conduct research. While working on the development of a flight simulator for training United States Navy aviators, he became convinced that a digital computer would be of significant value. In 1945 Forrester founded MIT’s Digital Computer Laboratory, where he helped develop Whirlwind I—an early, general-purpose digital computer used by the navy. As the project progressed, he realized that the memory storage system of Whirlwind I was slow and unreliable. This impressed Forrester with the need for a faster, more efficient method of storing large, frequently used segments of computer data.

In 1949 Forrester completed a three-dimensional magnetic-core memory system for computers by using a magnetic cell for both storing and switching information. It worked by passing electricity through small, magnetized iron rings. The electric current turned each individual ring either clockwise or counterclockwise to represent either a1 or a 0. This magnetic-core memory selected and retrieved stored information in a few microseconds. It was used in Whirlwind I, which became operational in 1951, and was the primary system of memory storage until the 1970s.

In 1951 Forrester joined MIT’s Lincoln Laboratory, where he applied Whirlwind I technology to early-warning air-defense systems for the U.S. Department of Defense. He was appointed professor of industrial management in the Sloan School of Management at MIT in 1956. Forrester’s books include Industrial Dynamics (1961), Principles of Systems (1968), Urban Dynamics (1969), World Dynamics (1971), and his Collected Works (1975).