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Massachusetts Institute of Technology, Magnetic Core Memory records

 Collection — Multiple Containers
Identifier: AC-0337

Scope and Contents of the Collection

The Forrester patent litigation extended over many years and resulted in a voluminous set of records. The records represent the documentation assembled and produced by MIT and the law firm of Kenway & Jenney in the course of the suits.

The collection fully documents the development of magnetic core memory and MIT's involvement in the patent litigation cases. It also provides information concerning the administrative handling of a major university patent and the relationship between a major research university and private industry. The records chronicle the growing disagreements between MIT and the Research Corporation which led to their contract termination in 1962.

The materials documenting Forrester's work include correspondence, memos, photographs, progress reports, and computation books. One of the most significant items is Forrester's notebook number 47, 1948 50 in which he wrote down his original plans for developing magnetic core memory (box 98). Also of special interest are legal statements made in 1964 by Forrester's assistant, William Papian (box 9, folder 8).

The collection includes a large series of microfilm created by the MIT Patent Administration Office as the documentation was gathered for the litigation. Because the microfilm was prepared in the order in which the material was received and no detailed indexing was done at the time, it is difficult to locate specific information on microfilm. It is believed that the originals and copies were filed in the collection once the documents were microfilmed. However, the film was retained because it may contain documents that no longer exist in paper form. A list of the microfilm records, written by Joyce Jones Ericson while the litigation proceeded, can be found in box 91.


  • 1932 - 1975


Access note

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Conditions Governing Use

Access to collections in the Department of Distinctive Collections is not authorization to publish. Please see the MIT Libraries Permissions Policy for permission information. Copyright of some items in this collection may be held by respective creators, not by the donor of the collection or MIT.

Historical note


The United States Patent Office issued Patent No. 2,736,880 to Professor Jay Forrester in 1956. The patent acknowledged Forrester's invention of magnetic core computer storage and set the stage for the development of high-speed digital computers.

The story of Forrester's invention of magnetic core memory began during World War II with a joint effort by MIT and the U.S. armed services to improve American defense capabilities. The original goal was the creation of an aircraft simulator, called the Aircraft Stability and Control Analyzer (ASCA), to aid the development of new improved aircraft.

The MIT unit involved in this project was the Servomechanisms Laboratory of the Department of Electrical Engineering. The laboratory, established in 1940, was headed by Gordon S. Brown, and assisted by Albert C. Hall, John O. Silvey, and Jay W. Forrester

ASCA itself was never built. Instead, the emphasis shifted from development of the simulator aircraft to creation of the computer mechanism which was the essential component of the simulator cockpit. The development of this computer, known as Project Whirlwind, represented a breakthrough in the way computers stored information, and resulted in the creation of a high-speed general purpose digital computer which subsequently became the prototype for most large-scale general purpose computers.

In the early years of Project Whirlwind, Forrester became aware of the limitations of the computer storage systems available. The then-popular electrostatic storage tubes lacked the speed and reliability required for the project. Forrester's solution was the development of an array of magnetic materials for storing information. The new storage system, called magnetic core memory, consisted of honeycombs of minute magnetic cores strung on wires through which storage information was read to electronic circuits in the computer.

Magnetic core memory provided a high degree of speed and level of reliability. Any bit of information stored in the memory could be extracted almost immediately rather than by a sequential search along magnetic drums, tapes, disks, or the electrostatic storage tubes. The method was quickly adopted by others in the computer field. In 1953, Raytheon, Remington Rand, and RCA shifted commercial machine storage emphasis to magnetic core storage, followed one year later by IBM.

A history of Project Whirlwind is recounted in Project Whirlwind: A Case History in Contemporary Technology by Kent C. Redmond and Thomas M. Smith (Bedford, Mass.: Digital Press, 1980).


Dr. Jan Rajchman - RCA

As soon as it was issued, the Forrester patent for magnetic core memory was contested by Dr. Jan Rajchman, an RCA researcher who had filed a similar patent application eight months before. Forrester and MIT were represented by the Research Corporation, a non-profit organization which handled inventions for universities. In 1935, MIT had entered into a contractual agreement with Research Corporation regarding inventions assigned to MIT by its faculty and research staff. The Research Corporation was to evaluate the inventions, obtain patents on them, and secure their use through licensing to industry. The royalty income was divided between MIT, Research Corporation, and the inventor.

Rajchman asked the Patent Office to declare interference, a legal term that means there is doubt as to whose claim is valid. If interference is declared, the patent is suspended until a determination of inventorship is made. The Patent Office agreed to declare interference regarding the Forrester patent.

Rajchman did not dispute that Forrester had been first to conceive of the idea. Rather, his case revolved around two major claims. First, he argued that Forrester had not reduced his idea to practice before filing his patent application. "Reduction to practice" means translating a concept into reality. Second, he argued that Forrester had not been "continuously diligent" in attempting to reduce to practice during the time between Rajchman's patent filing date (September 30, 1950) and Forrester's (May 1951). This claim meant that Forrester did not work continuously toward constructing his invention during this time period.

Rajchman did not question Forrester's diligence from September to December 1950, or from April to May 1951. The specific time period at issue was December 1950 to March 1951. Rajchman claimed that work on the invention had come to a standstill or had been abandoned by December 1950. He argued that William Papian, one of Forrester's key research assistants, discovered at a March 1951 meeting that Rajchman was working along the same lines. This knowledge, Rajchman contended, spurred Papian into renewed activity.

Since Rajchman's patent application filing date preceded Forrester's, Rajchman was designated the senior party to the case. As the junior party, Forrester had the burden of proving his case. Forrester contended that tests performed in October 1950 by Papian constituted reduction to practice, and that continuous work was performed during the time in question. For evidence, Forrester depended primarily on biweekly reports, laboratory notebooks, and oral testimony provided by those involved in the research. In March 1961, the Patent Office issued its decision. It concluded that the October 1950 tests did not constitute reduction to practice nor did it believe Forrester had proved diligence during the crucial period between December 1950 and March 1951. Consequently, the Patent Office awarded priority of inventorship to Jan Rajchman.

The Research Corporation filed a civil action in New York and sought to reverse the Patent Office's decision on prior inventorship. It also charged RCA with infringement of the Forrester patent.


IBM was involved in Project Whirlwind from the early stages of its development. In 1952, MIT personnel selected IBM to work with the Institute to augment the engineering design capability of the Whirlwind computer and to prepare for computer production.

After IBM began manufacturing computers with magnetic core memory systems, disagreement arose regarding the amount of royalties IBM should pay MIT for magnetic core memory. IBM and MIT differed in their assessments of the degree to which each had contributed to the development of magnetic core memory systems.

In 1961, MIT proposed that settlement negotiations be formally conducted with IBM concerning this matter. MIT rejected IBM's initial offer of $1 2 million as being too small. IBM countered that magnetic core memory was not worth more because it would soon be obsolete.

In July 1962, the Research Corporation, which was also conducting negotiations with IBM, filed a suit charging the firm with infringement of the Forrester patent. MIT officials, however, continued to feel that negotiations were the best way to proceed, and talks between MIT and IBM continued. Talks were also going on between RCA and MIT while the appeal of the interference decision was pending. The negotiations with IBM and RCA were closely related. Attorneys for MIT believed it was imperative to prove Forrester's inventorship in the RCA case before settling with IBM.

In March 1963, MIT terminated its relationship with the Research Corporation, bought the rights to the Forrester patent, and became a co-plaintiff in the RCA and IBM litigations. The Research Corporation claimed MIT underestimated the value of the patent and succumbed to pressure tactics by IBM to keep royalty rates low. MIT argued that it was the Research Corporation which had initially doubted the value of the Forrester patent, and claimed that excessively high royalty demands would hurt its relationship with IBM and with other computer companies. As an active participant in the suits, MIT sought to reverse the Patent Board's decision in the interference case and thus open the way to concluding the IBM and RCA cases. To do so, MIT needed to document the key period between December 1950 and March 1951.

Mr. James Hastings and Ms. Joyce Jones Ericson of MIT's Patent Administration Office (formerly the Research Administration) performed the tasks of locating, collecting, and indexing documents relevant to this time period. Their efforts covered a broad range of activities. Indeed, the title of one of the memos in this collection is entitled "Treasure Hunt," a good indication of the type of activity involved. The major thrust of their investigation was to gather hard evidence concerning Forrester's work and to ascertain the exact relationship between Rajchman's and Forrester's work. What did Rajchman know of Forrester's work? When and how could he have learned of it? People who knew Rajchman were contacted, and his activities were investigated. MIT Alumni Placement Office files were checked to see if any MIT Electrical Engineering students worked under Rajchman. Travel vouchers were located to see which people may have met which others at conferences. Telephone bills were uncovered to see who might have talked to the concerned parties. People were asked to recollect past conversations. The repositories that received Forrester's published works were checked to see who might have read the works and when. Purchase orders for core memory components were located to ascertain exactly when different stages of magnetic core memory production occurred. Laboratory notebooks were analyzed.

MIT's efforts were successful. In 1964, the cases against RCA and IBM were settled out of court by negotiated settlements. RCA withdrew its claims to any portion of the Forrester patent. MIT agreed to let RCA use the invention under a combination of royalty-free and royalty-bearing licenses. Under this agreement, RCA paid no royalties for memory systems sold as part of RCA computers. RCA would pay a royalty of 1/7 cent per bit on apparatus made by RCA for sale by other firms. MIT agreed to grant, upon request of RCA, royalty-free licenses to RCA licensees under claims that were in interference.

The IBM suit was ended after MIT granted a license to the corporation. In return, IBM paid MIT $13 million for "past and future use" of the magnetic core memory.

The resolution of the IBM and RCA cases opened the way for settlements with other major companies that manufactured magnetic core memory systems. The negotiations centered primarily around the determination of an equitable royalty settlement. The companies involved included General Electric, Sperry Rand, Seeburg, Indiana General Corporation, Burroughs, Digital Equipment Corporation, AMPEX, National Cash Register, and Fabritek. All but Digital Equipment Corporation were settled by lump sum settlements. Settlement with Digital Equipment Corporation was reached on a running royalty basis. Disputes over the size of royalty payments between MIT and AMPEX, Fabritek, and National Cash Register led to further litigation.


97.2 Cubic Feet (90 record cartons, 6 flat boxes, 1 tube, 1 half manuscript box)

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Materials are stored off-site. Advance notice is required for use.

Related Materials

Additional materials relating to the Whirlwind Project

Massachusetts Institute of Technology. Office of the President, 1930 - 1959
Massachusetts Institute of Technology. School of Engineering, Office of the Dean, 1960-1969
MIT Corporation, Office of the Chairman, 1959 71
Project Whirlwind
Gordon Stanley Brown papers

Processing Information note

Some collection descriptions are based on legacy data and may be incomplete or contain inaccuracies. Description may change pending verification. Please contact the MIT Department of Distinctive Collections if you notice any errors or discrepancies.

Guide to the Massachusetts Institute of Technology Magnetic Core Memory Records, AC.0337
Ready For Review
Finding aid prepared by Elaine Stein Primack, Amy Sugarman; Mark Vargas, Julie Schmittdiel
Copyright 1984; 1989
Description rules
Describing Archives: A Content Standard
Language of description
Script of description
Processing of a portion of this collection was funded by a grant from the U.S. Office of Education, Title II-C.

Repository Details

Part of the Massachusetts Institute of Technology. Libraries. Department of Distinctive Collections Repository

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