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IEE Proceedings E (Computers and Digital Techniques)

Volume 131, Issue 3, May 1984

Volumes & issues:

Volume 131, Issue 3

May 1984

Editorial. Technical Notes
Quad encoded display
  • Author(s): D.J. Milford  and  P.J. Willis
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 131, Issue 3, p. 70 –75
  • DOI:  10.1049/ip-e.1984.0012
  • Type: Article
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  • p. 70 –75 (6)
    A colour raster display system based on picture encoding is described. Encoding pictures as a means of data compression has a long history and is a technique of interest to anyone working with complex pictures. Its primary value is the lower bandwidths required of transmission channels, but its more frugal use of store is not to be overlooked. A quad tree as a means of encoding area-coherent pictures is used because it retains spatial information in a form which is still amenable to processing. The combination of this with compression makes this a particularly useful form of coding for raster-style colour pictures, and this paper addresses the problems which had to be overcome in order to construct a display directly exploiting the quad tree and related forms. The potential of such a display for rapidly handling very large amounts of pictorial data and for application to picture-archive retrieval is also discussed. The system has been constructed, is fully operational and incorporates roam and zoom operations. Sample pictures are included.
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Processing of inverted files in magnetic-bubble memories
  • Author(s): M. Zaki  and  F. Elboraey
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 131, Issue 3, p. 76 –88
  • DOI:  10.1049/ip-e.1984.0013
  • Type: Article
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  • p. 76 –88 (13)
    In this paper the applicability of magnetic-bubble memories to the processing of inverted files is discussed. Four novel models of magnetic-bubble memories are presented to demonstrate storage structures and data processing. The first model employs an organisation of major/minor loops. On the basis of such an organisation a uniform ladder is formed so that the data can be rearranged by using four operations: global shift, detached shift, exchange and delta exchange. The second model makes use of the on-chip decoder (also known as the self-contained magnetic-bubble-memory chip). For this model a hashing scheme is relied upon to perform the required data operations. The third and fourth models are different combinations of the former two models. The latter two models provide a relatively-high-speed performance as well as a reasonable system complexity. For each model the algorithms of data retrieval, sorting, deletion, insertion and updating are given. A comparison of the four models has been carried out in order to determine the most convenient magnetic-bubble-memory structure for the processing of inverted files.
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Fast iterative algorithm for reconstruction from divergent-ray projections
  • Author(s): C.E. Goutis  and  S.N. Drossos
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 131, Issue 3, p. 89 –96
  • DOI:  10.1049/ip-e.1984.0014
  • Type: Article
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  • p. 89 –96 (8)
    A convergent algorithm is introduced which solves the exact system relating the Lagrange multipliers and the projections using the successive relaxation method without any approximation. The system gives the minimum-energy solution which is different from that of the convolution algorithm, but it is the same as the ART reconstruction except that it discretises the Lagrange multipliers instead of the image. Its reconstructions are substantially better than those of the convolution algorithm. Although the new algorithm uses the exact matrix of this system, its speed is very high because it utilises the special matrix structure; namely the areas of equal elements. The statistics of the error between the ‘true’ projections and the projections corresponding to the reconstruction can be made the same as the noise statistics in the projection data, but the algorithm does not aim to produce the minimum norm solution to the problem of fitting noisy data. The number of projections N should be related to the number of measurements per projection P by P = vN/2, where v is an integer. Computed results verifying these conclusions are included. The algorithm can also use the object boundaries to improve its reconstruction.
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Technical note. Overflow detection in a redundant residue number system
Technical note. Approach for register allocation in microprogram generation
  • Author(s): E. Luque  and  A. Ripoll
  • Source: IEE Proceedings E (Computers and Digital Techniques), Volume 131, Issue 3, p. 99 –101
  • DOI:  10.1049/ip-e.1984.0016
  • Type: Article
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  • p. 99 –101 (3)
    A dynamic procedure for the allocation of internal registers of a microprogrammable system is described. The rules of this procedure are developed to yield an optimal allocation that minimises the execution time of the microprogram generated. The method assumes that the control flow of the program to be microcoded is represented by a directed graph. The allocation and deallocation of the variables to the registers is carried out in each edge in the graph. The selection of the variables to be assigned to the registers in each node is performed using integer linear programming.
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Digital Systems with Algorithm Implementation
Programming System Methodologies

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