Project History: Magnetic Core Memory

Magnetic core memory replaced vacuum tubes and mercury delay lines with a much more compact and reliable technology. Jay Forrester, who was head of the Whirlwind computer project, invented core memory at MIT in the late 1940s. Whirlwind was MITís first digital computer and the first digital computer built specifically for real-time control. IBM then licensed the technology and core memory became commonplace much of the first and second-generation of IBM computers. Semiconductor memories largely replaced magnetic cores in the 1970s, but they remained in use for many years in mission-critical and high-reliability applications. The Apollo Guidance Computer, for example (another project history) used core memory, as did the Space Shuttle until a recent computer upgrade.

This project history will work primarily with the core memory collection in the MIT archives, one of the richest sets of documentation for a particular invention that exists. A lawsuit was filed over the patent rights to the invention, so many lawyers spent a great deal of time documenting the invention and documenting the files. Forrester was a meticulous note taker and recorder of data, so his own thought process and the work of several of his students can be reconstructed with relative ease. Ken Olson, founder of Digital Equipment Corporation, was heavily involved as the liaison between MIT and IBM.

Possible themes: birth of magnetic storage, critical developments in computing, relationships between innovations in components and innovations in systems, radical design, from invention to mass-produced product, cold-war technology and computing.

Engineering Concentration: Electrodynamics and Energy Systems; Devices, Circuits, and Systems.

Secondary Sources:

Memories that Shaped an Industry, by Emerson Pugh

Project Whirlwind, by Kent Redmond and Thomas Smith

The Closed World, Paul Edwards

System Dynamics, Jay Forrester

Archival Sources:

MIT Archives, AC 337 Magnetic Core Memory Collection

Forrester Notebooks (series I, box 4)

Ken Olson Notebooks (box 8, folders 19-21)

Chronological File

Possible Contacts / Interviews:

Jay Forrester, MIT Sloan School

Ken Olson, DEC

William Papian, student of Forrester who developed core memory systems

Perry Crawford, who gave Forrester the idea to switch from analog to digital computing