Lincoln Laboratory. Division 6

Scope and Contents Division 6 Memo M-4153. Magnetic ferrites which have square hysteresis loops are being used as memory elements in high-speed digital computers. The limiting factor in memory reliability is the noise generated by the magnetic cores which are subjected to field excitations of amplitude insufficient to cause a reversal of magnetization. The occurrence of such excitations (half-amplitude pulses) at any given core in almost any possible sequence is inherent in the two-to-one coincident-current...

Scope and Contents MIT DIC 6889. Project Whirlwind Memo M-3059. After a short discussion of the factors which influence the incremental permeability, three different methods are discussed which should give a large change in incremental permeability with a change of the biasing field. The first requires a grain-oriented magnetic tape and take advantage of demagnetizing fields. The second requires a material with a square B-H loop, a low coercive force, and a large maximum permeability. The third requires a...

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Division 6 Memo M-3351. Memorandum providing a time schedule for machine evaluation tests of XD-1. The nature and purpose of evaluation tests performed on XD-1 and its associated equipment was outlined in "XD-1 Test Specifications" Memorandum 6M-3271, by J. A. O'Brien, 10 January 1955.

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Division 6 Memo M-3793. Technical Information Releases were used for equipment specifications and operational specifications for both the prototype and production machines.

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Division 6 Memo M-4226. Describes a cryotron tree switch, the initial conditions for the various transients, and the circuit parameter value. A simple method for calculating the pole zero pattern is found. Finally, an asymptotic expression is found for the slowest and fastest exponentials in a 2n position switch. Includes: introduction, cryotron, tree switch, analysis, numerical solution of pole and zero locations, summary, table and figures.

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Division 6 Memo M-3316. Memorandum discussing transistors and how they are made to pass large currents as needed in magnetic memories by turning off the currents while the transistors are being switched. Includes diagram of transistor memory driver.

Scope and Contents Project Whirlwind Memo VI L-84. In Lincoln Laboratory Technical Memorandum No. 20, which describes the proposed Transition System for Air Defense, Section VIII indicates that a study was being made regarding the cost and time factors for an initial sector. This memorandum summarizes this information for a proposal representing the best way to provide the maximum amount of coverage at the earliest practical date. Includes the following information: introduction, conditions on which the...

Scope and Contents MIT DIC 6889. Project Whirlwind Memo M-2629. The ferrite single-crystal-synthesis program of the Bell Telephone Laboratories was investigated. Information on some experimental techniques for measurement about to be undertaken in this laboratory was also obtained. Galt reported some recent work on microwave resonance in nickel ferrite which suggests a general technique for the measurement of the heat of activation for various electron-transfer relaxation phenomena. A brief outline is given to...

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MIT DIC 6889. Project Whirlwind Memo M-2778. A trip was made to various laboratories investigating ferroelectric and ferromagnetic materials for information storage and switching. Information is listed by topics.

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MIT DIC 6889. Project Whirlwind Memo M-2843. A trip was made to the Burroughs Research Center to discuss magnetic-core computer components and fabrication of metal cores. They are planning to make and improve metal cores and they have used magnetic cores in logical switching applications.

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MIT DIC 6889. Project Whirlwind Memo M-2398. The Linde Corporation is growing ferrite single crystals by the Verneuil process. They are of interest to this laboratory for basic studies of the switching mechanism of ferrites.

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Division 6 Memo M-3495. NSA in Washington submitted to Philco a purchase description for a computer, SOLO, to be built with an SBT control and arithmetic unit and a 4O96 register ferrite core memory. NSA and Group 63 agreed to maintain close contact regarding their respective transistor computer projects. Present at the discussion: (NSA) Joseph J. Eachus, Howard Campaigne, Roger Moulton, C. R. Blair, Douglas Hogan, A. E. Slade.

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MIT DIC 6889. Project Whirlwind Memo M-2483. Review of the progress in memory core production at RCA Victor in Camden is encouraging but considerable stabilization remains to be accomplished in the process, particularly in the pressing and firing operations. Particular care in testing sample batches should be directed toward checking reproducibility from batch to batch as their estimates are perhaps a bit optimistic about reproducibility.

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Project Whirlwind Memo M-2669. Silver migration occurs easily through and across the surface of a variety of materials in the presence of moisture and unipolar potential. The behavior of silver is peculiar in that it may migrate more easily than any other metal. It is recommended that no silver be used in contact with laminated plastic materials, where potential is present, in equipment which is intended to operate dependably for long periods of time.

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MIT DIC 6889. Project Whirlwind Controlled Distribution Memo 6D-107. Memory units and matrix switches using new square-loop ferrite material increase speed and reliability of digital computers. Storage units with arbitrary-access and read-out time of five microseconds or less makes stored-information rapidly available without scanning time required by other systems. Reprinted from Electronics, February 1956.

Scope and Contents MIT DIC 6889. Project Whirlwind Memo M-2482. The Tube Laboratory at IBM under Mr. John Little has received the assignment of investigating ferrite memory core production. During the past summer, the study was initiated and although the project is not as yet fully staffed certain phases, primarily of a mechanical and materials handling nature, have already gotten under way. The work with binders for the powder compacts is well done and shows rapid progress. Ingenious ways of evaluating binder...

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Project Whirlwind Memo VI L-94. Description of a visit by two Lincoln Laboratory staff members to the Remington Rand office in Washington and to see the ONR Logistics computer at George Washington University.

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Project Whirlwind Memo M-2896. Memorandum on procedures for advance notification of visits to IBM.

Scope and Contents Project Whirlwind Memo M-2332. A recent trip to the West Coast included visits to several laboratories engaged in the development of magnetic materials for digital-computer applications. Evaporated molybdenum Permalloy cores at NBS, Corona, have rectangular hysteresis loops but high coercivities. At UCLA, lithium ferrite is being investigated for memory-core applications by a group under the supervision of Prof. W. D. Hershberger; usable materials have been obtained. An investigation of the...

Scope and Contents MIT DIC 6889. Project Whirlwind Memo M-2943. After an examination of the manner in which x-ray techniques may be applied to a magnetic materials research program, the applications most meaningful to our particular interests have been selected. It is apparent that our program will achieve the most benefit from diffraction work of both service and research character. At present, x-ray fluorescent analysis does not seem to be well adapted to our needs. Equipment requirements are listed and...

Scope and Contents Division 6 Memo M-3526. Recent innovations in memory plane unit assembly made it desirable to install the Z and sense windings before the X-Y test could be performed. Sixteen unit planes were assembled and tested in different sequences in order to determine which assembly and testing sequence was most efficient. The test results while not conclusive did seem to indicate that an intermediate X-Y test were not necessary when the cores were subjected to a second production test previous to...

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Division 6 Memo M-3881. Second evaluation of the CD addressable drums performed on 13 July 1955. Includes: physical and logical status of XD-1; reliability; margins and margin history; shock tests; and conclusions.

Scope and Contents Division 6 Memo M-3669. The CD side of the drums was systems tested and was now part of the XD-1. However, as anticipated by the drum system engineers, the drums performed very poorly during the evaluation tests. The percentage of usable assigned time was 73% during the time assigned to MIT and 74.5% for the time during which IBM was running reliability programs and utility programs. Most of the low margins found during the last evaluation were improved. In general, the reliability of the...

Scope and Contents Division 6 Memo M-4270. The reliability of the XD-1 system has in general improved since the last report was issued (Memo 6M-4100 covering November, 1955). Overall reliability - up from 89% in December to 95% in February. Mean-good time between failures: No appreciable change. Lowest - 3.0 hours/biweekly period. Highest - 4.9 hours/biweekly period. Assigned time: Increased almost to the 168 hour per week limit during January, February and March. The tape drives are giving excessive trouble;...

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Division 6 Memo M-3271. Description of the formation of a section within Group 62 organized to write test specifications for the XD-1 equipment to evaluate its performance. Lists the objectives of the XD-1 test specifications and the series of tests to be written.

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Project Whirlwind Memo M-2842. A self-balancing bridge is utilized in conjunction with an "and" and an "or" gate input to satisfy the wave form and gating specifications on the driver for a magnetic core memory digit plane winding.