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IBM Journal of Research and Development

Issue 3 • Date May 1995

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Displaying Results 1 - 6 of 6
  • A walk along the branches of the extended Farey Tree

    Publication Year: 1995 , Page(s): 283 - 294
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (938 KB)  

    The rational numbers can be presented as the set of vertices of a degree-tree tree. If p/q and p'/q' are two rational numbers written in lowest terms, the difference pq'—p'q depends only on the shape of the path joining p/q to p'/q' on this tree. View full abstract»

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  • Properties of delay-cost scheduling in time-sharing systems

    Publication Year: 1995 , Page(s): 295 - 314
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1611 KB)  

    We consider properties of time-sharing schedulers with operations based on an economic measure termed the delay cost, and relate these to scheduling policies such as those used in VM and MVS. One of these policies, deadline scheduling, is shown to be potentially unstable. We develop delay-cost schedulers that meet similar performance objectives under quasi-equilibrium conditions but which are stable under rapidly varying loads. View full abstract»

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  • Flexible oblivious router architecture

    Publication Year: 1995 , Page(s): 315 - 329
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1350 KB)  

    In this paper we present a router architecture that accommodates a family of oblivious routing algorithms. The architecture is suitable for current technologies, and it is intended for multiprocessor and massively parallel systems. Via the proposed architecture, we suggest that general-purpose routers can be designed to accommodate a variety of multiprocessor interconnection networks. In particular, the routing algorithms of those interconnection structures that can be classified as trees, cubes, meshes, and multistage interconnection networks can be accommodated with a flexible, easily implemented architecture. Our investigation strongly suggests that a common design can satisfy at least forty network topologies with the introduction of a few instructions that are very simple to implement. The overall conclusion is that general-purpose cost-effective routers can potentially be designed that perform equally as well as customized routing logic, suggesting the possibility of a common router for multiple interconnection networks. Furthermore, the proposed architecture provides programming capabilities that allow other oblivious routing algorithms not considered in our investigation to be accommodated. View full abstract»

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  • A unified table-based Viterbi subset decoder for high-speed voice-band modems

    Publication Year: 1995 , Page(s): 331 - 334
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (345 KB)  

    A unified table-based subset decoder for the Viterbi algorithm has been designed which is capable of decoding any constellation size for any data rate scheme of the CCITT (Comite Consultatif International Telegraphique et Telephonique) V.32, V.32bis, and IBM V.32ter high-speed, full-duplex voice-band modem implementations with a constant number of computations. In addition, no error is introduced as a result of this subset decoding. The data rates include trellis coded 7200-, 9600-, 12000-, 14400-, 16800-, and 19200-bps rates. The number of computations necessary to perform the decoding is the same for any given data rate, resulting in reductions in computational complexity up to a factor of 32 in comparison to existing direct methods. The memory consumption of the decoder is relatively small and increases proportionally with data rate. View full abstract»

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  • Recent publications by IBM authors

    Publication Year: 1995 , Page(s): 335 - 348
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1129 KB)  

    The information listed here is supplied by the Institute for Scientific Information and other outside sources. Complete addresses are provided for the lead author of each publication. Journals and books are listed alphabetically by title; papers are listed sequentially for each journal. View full abstract»

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  • Recent IBM patents

    Publication Year: 1995 , Page(s): 349 - 368
    Save to Project icon | PDF file iconPDF (1415 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