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IBM Journal of Research and Development

Issue 5 • Date Sept. 1973

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Displaying Results 1 - 13 of 13
  • Decomposition of a Data Base and the Theory of Boolean Switching Functions

    Page(s): 374 - 386
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (646 KB)  

    The notion of a functional relation among the attributes of a data set can be fruitfully applied in the structuring of an information system. These relations are meaningful both to the user of the system in his semantic understanding of the data, and to the designer in implementing the system. An important equivalence between operations with functional relations and operations with analogous Boolean functions is demonstrated in this paper. The equivalence is computationally helpful in exploring the properties of a given set of functional relations, as well as in the task of partitioning a data set into subfiles for efficient implementation. View full abstract»

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  • Characterization of Program Paging in a Time-sharing Environment

    Page(s): 387 - 393
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (489 KB)  

    This paper describes a method for predicting the paging behavior of a program in a virtual memory multiprogramming environment. The effect of overall system activity on the program is summarized in one parameter, the page survival index. The model correlates well with observations taken on programs running under CP-67. The model can be used for paging load prediction, simulator input verification, and evaluation of program rearrangement and sharing. View full abstract»

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  • Response Time Characterization of an Information Retrieval System

    Page(s): 394 - 403
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (565 KB)  

    A methodology for computer performance evaluation based on the statistical characterization of response time is described. The results of its application to an information retrieval system are presented. The first part of the paper gives a general discussion of measurement techniques, data reduction procedures and the structure of the system being examined. A set of “system environment” parameters and a set of “job” parameters are then defined and appraised in terms of actual measurements collected over two different weekly periods. Various ways of using the statistical characterization for improving performance are then considered. View full abstract»

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  • An Analysis of Page Allocation Strategies for Multiprogramming Systems with Virtual Memory

    Page(s): 404 - 412
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    In a multiprogramming, virtual-memory computing system, many processes compete for the main storage page frames and CPU's of the real system. It is customary to define a subset of these processes called the “multiprogramming set” (MPS), and to allocate resources only to those processes currently in the MPS. Each process remains in the MPS for a limited time and is then demoted. The system paging manager controls the size of the MPS; it allocates the available page frames among the processes in the MPS and fetches appropriate pages into the page frames. View full abstract»

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  • A Decision-feedback Receiver for Channels with Strong Intersymbol Interference

    Page(s): 413 - 419
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (413 KB)  

    This paper deals with the problem of equalizing channels containing strong intersymbol interference. Typical of such channels are those of digital magnetic recording systems and data communication systems with partial-response signaling. First we discuss reasons that a conventional receiver with a linear equalizer cannot efficiently compensate for distortion in such channels. We then present a new receiver configuration in which the equalizer and quantizer are embedded in an inverse filter circuit that eliminates major intersymbol interference components. This configuration allows us to use a simple iteration algorithm to adaptively adjust the equalizer. Application of the scheme to digital magnetic recording data is discussed as an illustrative example. View full abstract»

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  • Lower Bounds for the Partitioning of Graphs

    Page(s): 420 - 425
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (385 KB)  

    Let a k-partition of a graph be a division of the vertices into k disjoint subsets containing m1 ≥ m2, …, ≥ mk vertices. Let Ec be the number of edges whose two vertices belong to different subsets. Let λ1 ≥ λ2, …, ≥ λk be the k largest eigenvalues of a matrix, which is the sum of the adjacency matrix of the graph plus any diagonal matrix U such that the sum of all the elements of the sum matrix is zero. Then given equation. A theorem is given that shows the effect of the maximum degree of any node being limited, and it is also shown that the right-hand side is a concave function of U. Computational studies are made of the ratio of upper bound to lower bound for the two-partition of a number of random graphs having up to 100 nodes. View full abstract»

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  • Dislocations in Gadolinium Gallium Garnet (Gd3Ga5O12): III. Nature of Prismatic Loops and Helical Dislocations

    Page(s): 426 - 429
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (309 KB)  

    Thin garnet films suitable for magnetic bubble devices can be made by depositing the film material onto nonmagnetic garnets such as Gd3Ga5O12 (GGG). The performance of these devices is influenced by the dislocation content of the films. This, in turn, depends on the dislocation content of the substrate. Dislocations in the substrate can be detected by means of the birefringence they induce, or from the etch pits formed where they meet the sample surface. Most of the dislocations revealed by these techniques have been climb loops around inclusions and helical dislocations. This paper describes an optical method for determining the sign of the stresses at inclusions and nature of loops and helical dislocations. The method has shown that iridium inclusions are compressed by the matrix and that the loops and helices in GGG are extrinsic; they grow either by the emission of vacancies or the absorption of interstitial atoms. View full abstract»

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  • Design and Characteristics of n-Channel Insulated-gate Field-effect Transistors

    Page(s): 430 - 442
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (650 KB)  

    An n-channel insulated-gate field-effect transistor technology established at IBM Research has served as the basis for further development leading to FET memory. Designs and characteristics of experimental devices of 500 and 1000 Å gate insulator thicknesses are presented, with particular attention to the effects of source-drain spacing. View full abstract»

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  • Theory and Operation of Space-charge-limited Transistors with Transverse Injection

    Page(s): 443 - 458
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (798 KB)  

    The development of a new device, called the space-charge-limited (SCL) transistor with transverse injection is reported in this paper. A theoretical model for space-charge-limited transistors, both npn and pnp, on high-resistivity silicon substrates is described and a quantitative analysis is given. Experimental results for SCL transistors are presented to support the model's validity. According to the model, current in SCL transistors is controlled by the base of a parallel-connected lateral transistor in two ways. First, the base of the parallel transistor controls the potential step in the high resistivity base of the SCL transistor. Second, the base of the parallel transistor injects carriers in the direction transverse to the SCL current flow. These carriers are of types opposite to those that carry the current flow in the SCL transistor and thus partly neutralize the space-charge in the current flow. The carriers propagate, predominantly by drift, across the high-resistivity base region of the SCL transistor. The resulting base transit time is about two orders of magnitude faster than that of a bipolar transistor with equal base width. No charge storage takes place in saturation. These features and the very low device capacitances make the SCL transistor attractive for low-power, fast-switching applications. Current gains as high as 70,000 are obtained at low current levels. The current gain decreases at higher current levels because the parallel lateral transistor turns on. It is also demonstrated that complementary pairs of SCL transistors can be fabricated with three masking steps, including metalization. View full abstract»

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  • Recent Papers by IBM Authors

    Page(s): 459 - 462
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (405 KB)  

    Reprints of the papers listed here can usually be obtained by writing directly to the authors. The authors' IBM divisions are identified as follows: ASDD is the Advanced Systems Development Division; DPD, Data Processing Division; FED, Field Engineering Division; FSD, Federal Systems Division; GPD General Products Division; GSD, General Systems Division; OPD, Ofice Products Division; RES, Research Division; SDD, System Development Division; SPD, System Products Division; and WTC, World Trade Corporation. Papers are listed alphabetically by name of journal. View full abstract»

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  • Recent IBM patents

    Page(s): 463 - 465
    Save to Project icon | PDF file iconPDF (326 KB)  
    Freely Available from IEEE
  • Authors

    Page(s): 466 - 468
    Save to Project icon | PDF file iconPDF (308 KB)  
    Freely Available from IEEE
  • Contents of previous issues

    Page(s): 469 - 471
    Save to Project icon | PDF file iconPDF (252 KB)  
    Freely Available from IEEE

Aims & Scope

The IBM Journal of Research and Development is a peer-reviewed technical journal, published bimonthly, which features the work of authors in the science, technology and engineering of information systems.

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Meet Our Editors

Editor-in-Chief
Clifford A. Pickover
IBM T. J. Watson Research Center