DOCSLIB.ORG

ICL Systems Journal

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ICL Systems Journal Volume 12 Issue 1 May 1997 Edition Journal ICL Systems Journal Editor Prof. V.A.J. Mailer ICL Professor Department of Computer Studies, Loughborough University, Loughborough, Leicestershire, LE11 3TU. Editorial Board V.A.J. Mailer (Editor) C.J. Mailer (Board Secretary) A.J. Boswell M.R. Miller (BT Laboratories) P.J. Cropper W. O'Riordan D.W. Davies FRS J.V. Panter G.E. Felton J.M.M. Pinkerton PFL Forbes E.C.P. Portman J. Flowlett A. Rowley N. Kawato (Fujitsu) M.J. Rigg M.H. Kay B. C. Warboys (Univ. of Manchester) F.F. Land P.G. Wharton All correspondence and papers to be considered for publication should be addressed to the Editor. The views expressed in the papers are those of the authors and do not nec­ essarily represent ICL policy. Published twice a year by Research and Advanced Technology, ICL, Bracknell. 1997 subscription rates (including postage & packing): UK and Europe Rest of World Annual subscription £72 $120 Single issues £43 $72 © 1997 International Computers Limited, Registered Office, ICL House, 1 High Street, Putney, London SW15 1SW. Registered in England 96056 ISSN 1364-310X ICL Systems Journal Volume 12 Issue 1 Contents Editorial i Java™—An overview 1 Nic Holt Mobile Agents—The new paradigm in computing 14 L. L. Thomsen and B. Thomsen The SY Node Design 41 G. Allt, P. DeSyllas, M. Duxbury, K. Hughes, K. Lo, J. Lysons and P.V. Rose Discovering associations in retail transactions using 73 Neural Networks O.V.D. Evans Methods for Developing Manufacturing Systems Architectures 89 S. Murgatroyd and R. Smethurst Demystifying Constraint Logic Programming 121 O.V.D. Evans Constraint Logic Programming 137 M. Wallace ECL'PS6—A Platform for Constraint Programming 159 M. Wallace, S. Novello and J. Schimpf Previous Issues 201 Guidance for Authors 211 ICL Systems Journal May 1997 i Front cover: Mobile Agents in action! See the paper, "Mobile Agents—The new paradigm in computing," in this issue. u ICL Systems Journal May 1997 Editorial The ICL Systems Journal normally avoids having issues devoted to a sin­ gle theme, except in exceptional circumstances. However, the practice of having a small number of papers on a related theme has been followed frequently, particularly when new fields of importance are emerging. In this issue, papers on three important areas are being published, namely, Java, Mobile Agents and Constraint Programming. The first two of these are, of course, related within the context of distributed computing and the Editor intends that papers on significant applications of these new technologies will follow in future issues. Constraint Programming, how­ ever, is not new and applications of it have been described in earlier issues. What makes a further set of papers timely is the development of a power­ ful new software platform, ECL'PS^, at IC-Parc, a research institute at Im­ perial College in London, of which ICL is one of the sponsors. This plat­ form enables the technology of Constraint Programming to be applied to a wide variety of difficult problems with much greater ease than hitherto. The Editor is aware that a number of people in the field of computing perceive the intellectual hurdle of Constraint Programming to be difficult to surmount. Consequently, two introductory papers have been invited from Owen Evans and Mark Wallace to provide readers with "a lift over this hurdle". These papers are followed by a comprehensive description of ECLiPSe, also written by Mark Wallace, together with some of his col­ leagues at IC-Parc. A paper on its application will follow in the next issue. V.A.J. Mailer ICL System s Journal May 1997 111 Java™ - an overview Nic Holt High Performance Systems, ICL, Manchester, UK Abstract The origins of Java can be traced back to the early 1990s when Sun engineers were investigating the requirements for cheap consumer devices capable of communicating with each other. In 1994, Sun rec­ ognised the potential of coupling Java technology with the World- Wide Web, paving the way for a new era of "Network Computing". Since then Java has become a cornerstone of Internet distributed com­ puting and all major IT industry suppliers have embraced Java tech­ nology in some form or other. This paper identifies the significant elements of Java technology, outlines the positioning of major IT sup­ pliers and discusses its potential influence on new business models based on distributed computing. 1. Introduction Java has become inextricably associated with the rapid evolution of Internet computing sparked by the introduction of the World-Wide Web and widely available Internet services. This vision is one of universally accessible on­ line information services supported by a global network infrastructure. Although the consumer market is likely to be more significant in the longer term, the immediate focus is on the potential business benefits of applying these technologies within organisations—the so-called Intranet. In the longer term, the distinction between Intranets and the Internet will become blurred. The emergence of commercial-strength secure distribution infrastructure overlaying the Internet will enable new models of inter- organisational collaboration and commerce, as well as intra-organisational operation. The question of the moment is whether the convergence of several technologies heralds a revolution in distributed computing, or whether the benefits of Java, relative to steady evolution of current approaches, are being over-hyped. There are major commercial issues at stake. In particular, the prevailing "WinTel" (Microsoft Windows/Intel) dominance of the (enterprise) desktop is under threat—a response to the massive perceived management costs of PCs, widely quoted as around $4,000 per PC per annum [Forrester, 1995]. ICL System s Journal May 1997 1 2. Background The origins of Java can be traced back to the early 1990s when Sun engineers started to investigate the requirements for cheap consumer devices with embedded processors, capable of communicating with each other. The short product life-cycle of the consumer market dictated that it should be possible to introduce upgraded products—including, significantly, the processors embedded within them—whilst maintaining previous investment in software and applications. Over the next two years a new language, "Oak" (later to be renamed Java), as well as an operating system (a precursor of JavaOS) and custom microprocessors (the Picojava architecture) were developed. In 1994, Sun recognised the potential of coupling the nascent Java technology with the burgeoning World-Wide Web, heralding the dawn of a new era of "Network Computing". Since then almost all major IT industry suppliers have embraced Java technology in some form or other. 3. What is Java? Java is a modem object-oriented programming language. The term "object- oriented" means that a program is written in terms of real-world objects and the actions that can be performed on them. This is rapidly becoming the preferred industry approach and is embodied in languages such as C++ and Visual Basic, as well as the distributed object architectures of Microsoft ActiveX and OMG CORBA. The emergence of self-contained objects offers the prospect of software "building-blocks" or components which can be simply integrated into sophisticated applications. Microsoft ActiveX, OpenDoc and Java Beans are examples of component software technologies. As a programming language, Java has several features which offer improvements over alternative languages. These include "safety features" which ensure more reliable programs, extensive libraries of useful services, a component-based approach to application construction and a natural fit with networked computing. Nonetheless, even with the benefits of Java it still requires skill and experience to write good software. Java's main distinguishing feature, however, is not in the language itself but in the means by which a Java program is executed on a computer. Normally, a program is issued in a (binary) form which is specific to the processor on which it is intended to run and, in some cases, specific to the combination of processor and operating system. Application vendors must make a separate investment in each target platform for each software product. This results in a huge barrier to entry into volume markets such as the desktop for alternatives to the Windows/Intel architecture. In contrast, Java is compiled to a machine-independent form known as Java byte-code. This can be thought of as the instruction set for an imaginary machine. A Java program is executed by a piece of software known as the Java VM (Virtual Machine), which interprets the byte-code form of the 2 ICL System s Journal May 1997 program. To achieve program portability, it is only necessary to ensure that the Java VM itself is available on each computer system—a once-off porting activity which can be undertaken independently. None of this approach is new. In the late 1970s, the University of California, San Diego, developed the UCSD Pascal system which made high- level programming feasible on personal computers. In the UCSD system, Pascal was compiled to a portable, interpreted form known as p-code. The limitations of Pascal, in particular its limited I/O features, eventually led to its demise at the hands of the C language. With aims similar to Java, the Royal Signals and Radar Establishment at Malvern (now DRA, Malvern) developed the Architecturally Neutral Distribution Format (ANDF) during the early 1990s, as a means of distributing software written in any source language in a machine independent form. Although technically sound, the concerns of software vendors that it would enable reverse engineering of programs distributed in ANDF prevented its widespread adoption. What distinguishes Java from its predecessors is the completeness of the "vision" promoted by SUN, including the language itself, a rich set of standard libraries, development tools, execution environments, inherent distribution & networking capabilities and, perhaps most importantly, a credible case.
Load more

Recommended publications
  • Vcf Pnw 2019
    VCF PNW 2019 http://vcfed.org/vcf-pnw/ Schedule Saturday 10:00 AM Museum opens and VCF PNW 2019 starts 11:00 AM Erik Klein, opening comments from VCFed.org Stephen M. Jones, opening comments from Living Computers:Museum+Labs 1:00 PM Joe Decuir, IEEE Fellow, Three generations of animation machines: Atari and Amiga 2:30 PM Geoff Pool, From Minix to GNU/Linux - A Retrospective 4:00 PM Chris Rutkowski, The birth of the Business PC - How volatile markets evolve 5:00 PM Museum closes - come back tomorrow! Sunday 10:00 AM Day two of VCF PNW 2019 begins 11:00 AM John Durno, The Lost Art of Telidon 1:00 PM Lars Brinkhoff, ITS: Incompatible Timesharing System 2:30 PM Steve Jamieson, A Brief History of British Computing 4:00 PM Presentation of show awards and wrap-up Exhibitors One of the defining attributes of a Vintage Computer Festival is that exhibits are interactive; VCF exhibitors put in an amazing amount of effort to not only bring their favorite pieces of computing history, but to make them come alive. Be sure to visit all of them, ask questions, play, learn, take pictures, etc. And consider coming back one day as an exhibitor yourself! Rick Bensene, Wang Laboratories’ Electronic Calculators, An exhibit of Wang Labs electronic calculators from their first mass-market calculator, the Wang LOCI-2, through the last of their calculators, the C-Series. The exhibit includes examples of nearly every series of electronic calculator that Wang Laboratories sold, unusual and rare peripheral devices, documentation, and ephemera relating to Wang Labs calculator business.
    [Show full text]
  • Validated Products List, 1995 No. 3: Programming Languages, Database
    NISTIR 5693 (Supersedes NISTIR 5629) VALIDATED PRODUCTS LIST Volume 1 1995 No. 3 Programming Languages Database Language SQL Graphics POSIX Computer Security Judy B. Kailey Product Data - IGES Editor U.S. DEPARTMENT OF COMMERCE Technology Administration National Institute of Standards and Technology Computer Systems Laboratory Software Standards Validation Group Gaithersburg, MD 20899 July 1995 QC 100 NIST .056 NO. 5693 1995 NISTIR 5693 (Supersedes NISTIR 5629) VALIDATED PRODUCTS LIST Volume 1 1995 No. 3 Programming Languages Database Language SQL Graphics POSIX Computer Security Judy B. Kailey Product Data - IGES Editor U.S. DEPARTMENT OF COMMERCE Technology Administration National Institute of Standards and Technology Computer Systems Laboratory Software Standards Validation Group Gaithersburg, MD 20899 July 1995 (Supersedes April 1995 issue) U.S. DEPARTMENT OF COMMERCE Ronald H. Brown, Secretary TECHNOLOGY ADMINISTRATION Mary L. Good, Under Secretary for Technology NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY Arati Prabhakar, Director FOREWORD The Validated Products List (VPL) identifies information technology products that have been tested for conformance to Federal Information Processing Standards (FIPS) in accordance with Computer Systems Laboratory (CSL) conformance testing procedures, and have a current validation certificate or registered test report. The VPL also contains information about the organizations, test methods and procedures that support the validation programs for the FIPS identified in this document. The VPL includes computer language processors for programming languages COBOL, Fortran, Ada, Pascal, C, M[UMPS], and database language SQL; computer graphic implementations for GKS, COM, PHIGS, and Raster Graphics; operating system implementations for POSIX; Open Systems Interconnection implementations; and computer security implementations for DES, MAC and Key Management.
    [Show full text]
  • Systems Corporation Pern SYSTEM OVERVIEW March 1984
    o PERn Systems Corporation PERn SYSTEM OVERVIEW o March 1984 This manual is for use with POS Release G.5 and subsequent releases until further notice. Copyri9ht(C) 19B3, 19Bi PERC Systems Corporation 2600 Liberty Avenue P. O. Box 2600 Pittsbur9h, PA 15230 (HZ) 355-0900 o o This document is not to be reproduced in any fonn or transmitted in whole or in part, without the prior written authorization of PERQ Systems Corporation. o The information in this document is subject to change without notice and should not be construed as a commitment by PERQ Systems Corporation. The company assumes no responsibility for any errors that may appear in this document. PERQ Systems Corporation will make every effort to keep customers apprised of all documentation changes as quickly as possible. The Reader's Comments card is distributed with this document to request users' critical evaluation to assist us in preparing future documentation. PERQ and PEROZ are trademarks of PERQ Systems Corporation. o - ii - --~---- ----------- PREFACE January 15, 1984 o PREFACE This manual is intended for new users of PERQ and PERQ2. The manual will familiarize you with the machines and get you started using either system. As you learn more about your system, you will find that it provides you with many facilities, both conveniences and necessities. This manual consists of three chapters. Chapter One describes the method to turn the system on and the bootstrap process. Chapter Two describes the PERQ and PERQ2 hardware. Chapter Three discusses the basic operation of the system software. Distinctions between the PERQ and PERQ2 are explicit.
    [Show full text]
  • Computer Conservation Society
    Issue Number 88 Winter 2019/20 Computer Conservation Society Aims and Objectives The Computer Conservation Society (CCS) is a co-operative venture between BCS, The Chartered Institute for IT; the Science Museum of London; and the Science and Industry Museum (SIM) in Manchester. The CCS was constituted in September 1989 as a Specialist Group of the British Computer Society. It is thus covered by the Royal Charter and charitable status of BCS. The objects of the Computer Conservation Society (“Society”) are: To promote the conservation, restoration and reconstruction of historic computing systems and to identify existing computing systems which may need to be archived in the future; To develop awareness of the importance of historic computing systems; To develop expertise in the conservation, restoration and reconstruction of historic computing systems; To represent the interests of the Society with other bodies; To promote the study of historic computing systems, their use and the history of the computer industry; To publish information of relevance to these objectives for the information of Society members and the wider public. Membership is open to anyone interested in computer conservation and the history of computing. The CCS is funded and supported by a grant from BCS and from donations. There are a number of active projects on specific computer restorations and early computer technologies and software. Younger people are especially encouraged to take part in order to achieve skills transfer. The CCS also enjoys a close relationship with the National Museum of Computing. Resurrection The Journal of the Computer Conservation Society ISSN 0958-7403 Number 88 Winter 2019/20 Contents Society Activity 2 News Round-Up 9 The Data Curator 10 Paul Cockshott From Tea Shops to Computer Company: The Improbable 15 Story of LEO John Aeberhard Book Review: Early Computing in Britain Ferranti Ltd.
    [Show full text]
  • Commerci Confidence
    COMMERCI CONFIDENCE perq.Files - perq files information. Modified: 23 oct 80 JPS. a list of all files used by Three Rivers Computer Corporation for software and hardware development of the perq system. *** warning: this list is not yet complete >OS.SOURCE - OPERATING SYSTEM SOURCES file name version file name on floppy short description. DYNAMIC.PAS 0.0 DYNAMI.PAS Dynamic allocation routines - New and Dispose. WRITER.PAS 0.0 WRITER.PAS Stream package output conversion routines. READER.PAS 0.0 READER.PAS Stream package input conversion routines. PSTRING.PAS 0.0 PSTRIN.PAS String manipulation package. STREAM.PAS 0.0 STREAM.PAS Stream package base routines - Get and Put. SYSTEM.PAS A.lS SYSTEM.PAS Operating system main program. CODECONST.PAS CODECO.PAS Linker and loader constant definitions. CODETYPE.PAS CODETY.PAS Linker and loader type definitions. LOADERl.PAS LOADRl.PAS Loader constant definitions. LOADER2.PAS LOADR2.PAS Loader type definitions. LOADER3.PAS LOADR3.PAS Loader var definitions. LOADER4.PAS LOADR4.PAS Loader procedure definiiions. SEGNUMBERS.PAS 0.0 SEGNUM.PAS System segment number constants. MEMORY.PAS 1.1 MEMORY.PAS Memory manager. , SCREEN.PAS 0.0 SCREEN.PAS PAGE 2 Screen manager. SYSVERS.PAS ' 0.0 SYSVER.PAS System ve~sion number conversion routine. CMDPARSE.PAS 1.0 CMDPAR.PAS Command parser. FILESYSTEM.PAS 2.0 FILESY.PAS File system. RASTER. PAS 0.0 RASTER.PAS Raster-op definitions. LINEDRAW.PAS 0.0 LINEDR.PAS Line drawing interface module. IOERRS.PAS 0.0 IOERRS.PAS Input/output error number constants. IO.PAS 2.2 IO.PAS Input/output manager.
    [Show full text]
  • PERQ Workstations by R. D. Davis
    PERQ Workstations R. D. Davis Last Updated: November 6, 2003 from the Sept. 7, 1991 edition. 2 Contents 1 Preface and Dedication 11 2 History 13 2.1 PERQ History as Told by Those Who Were There . 13 2.2 PERQ History as Otherwise Researched . 16 2.3 Late 1960's . 16 2.4 1972/1973 . 17 2.5 1973 . 17 2.6 1974 . 17 2.7 1975 . 18 2.8 1976 . 18 2.9 Late 1970's . 18 2.10 1978 . 18 2.11 1979 . 19 2.12 1980 . 19 2.13 1981 . 20 2.14 1982/1983: . 22 2.15 1983-1984? . 22 2.16 1984: . 23 2.17 1985 . 24 2.18 1986: . 25 2.19 1986/1987 . 26 2.20 1997 . 27 2.21 Things whose time period is questionable . 27 3 Accent Systems Corp. 31 4 More PERQ History 33 4.1 Graphic Wonder . 33 3 4 CONTENTS 4.1.1 Historical notes from Chris Lamb . 35 4.2 Alt.sys.perq . 36 4.3 PERQ-Fanatics Mailing Lists . 36 4.4 Original uCode . 37 5 The Accent OS 39 5.1 The Accent Kernel . 42 5.2 Co-Equal Environments . 44 5.3 Accent Window Manager: Sapphire . 44 5.4 Matchmaker . 45 5.5 Microprogramming . 45 5.6 Other Info. 46 5.7 Accent and Printing/Publishing . 46 5.8 Porting POS Code to Accent . 47 5.9 Accent S5 . 47 5.10 Naming of Accent . 47 6 The Action List 49 7 Adverts and Etc. 53 7.1 PERQ-1 . 53 7.1.1 PERQ Systems and cooperative agreements: .
    [Show full text]
  • Chapter 3. the Persistent Programming Language, PS-Algol
    https://theses.gla.ac.uk/ Theses Digitisation: https://www.gla.ac.uk/myglasgow/research/enlighten/theses/digitisation/ This is a digitised version of the original print thesis. Copyright and moral rights for this work are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This work cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Enlighten: Theses https://theses.gla.ac.uk/ [email protected] On The Utilisation of Persistent Programming Environments Richard Cooper A thesis submitted to the Faculty of Science, University of Glasgow For the degree of Doctor of Philosophy September, 1989 © R. L. Cooper, 1989 ProQuest Number: 10999281 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10999281 Published by ProQuest LLC(2018). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC.
    [Show full text]
  • Computing Laboratory Newsletter
    University of St Andrews COMPUTING LABORATORY ICL PERQ COMPUTER USE� NOTE ON DATATRIEVE PADACC MICROCOMPUTER SOFTWARE MICROINV OXFORD CONCORDANCE PACKAGE GIGI COLOUR GRAPHICS TERMINAL BENSON ELECTROSTATIC PLOT TER ABERDEEN HONEYWELL SYSTEM VAX SERVICEABILITY FIGURES NEWSLETTER October 1982 North Haugh, St Andrews KY16 9SX, Scotland. Telephone 76161 (1 ) I ..... ', '-, ICL PERQ COMPUTER MICROCOMPUTER SO�TWARE The Laboratory has been a'warded an ICL PERQ The Microprocessor Group has recently purchased three software system t�at is to ���e available to computer �sers within packages from �!icroPro which run under the CP/M operating system. They "he PERQ is a V'?P' )"i':Hf'Jl single-user system c::msisting of a are related products viz. Wordstar, Datastar and Calcstar. The processo;:: corr,parat' Le �,_,wer (for some applications at least) to a programs have been installed on a superbrain and are available for V,.",.X, 1 megabyte of r:emcry. a 24 megabyte fixed d an 8 inch floppy assessment or use by users. Anyone interested shoulc contact either disk, a Lit pad, � kevL0ar� and a high resolution 1024 by 768 pixe]s) Phi 1 Rob ertson (ext 8112) or Bruce Campbel1 (ext 8114) in the screen. A has 31so been attached local Because of its Computing Laboratory. pO'."er the RQ is c:apiwle 0 performing quite ticated graphiCS, l.ncluding animation. Word�t�r is a screen-oriented text handler which has integrated , , prlnt facll�t�es. The entry of text gives a displa' of the text as it The so f tware ava�laLle for use with the PERQ is Ilmited at preseGt will be output and carries out such tasks as right j ustification and that 'dhi ch is ther is nt't necessar i ly pe rmunent .
    [Show full text]
  • A Persistent Graphics Facility for the ICL PERQ Computer”
    This paper should be referenced as: Morrison, R., Brown, A.L., Bailey, P.J., Davie, A.J.T. & Dearle, A. “A Persistent Graphics Facility for the ICL PERQ Computer”. Software – Practice and Experience 16, 4 (1986) pp 351-367. A Persistent Graphics Facility for the ICL Perq R. Morrison, A.L. Brown, P.J. Bailey, A.J.T. Davie, A. Dearle. Department of Computational Science, University of St Andrews, North Haugh, St Andrews KY16 9SX, Scotland. Summary The facilities of the PS-algol programming language are described in this paper to show how they may be used to provide an integrated programming support environment. The persistent store mechanism and the secure transaction facilities provide the basic environment in which an integrated system may be implemented. In particular the paper makes use of the data type picture of PS-algol to show how such an environment may be built for a graphics system ideal for use with a medium range computer workstation. An implementation of a picture editor on the ICL PERQ workstation is described to show the utility of the system. Keywords: Persistent store graphics algol transactions workstation ICL PERQ Introduction The inclusion of a graphics facility in a language that supports an integrated persistent environment yields an ideal programming environment for a medium range graphics workstation such as the ICL PERQ[7]. The integrated persistent store allows data to be stored and retrieved automatically from user named databases. If one of the legal data types in the language is a picture then pictures may be stored along with any of the other legal data objects such as integers, vectors or procedures.
    [Show full text]
  • ICL Technical Journal Volume 5 Issue 3
    TECHniCAl j o u m n i Volume 5 Issue 3 May 1987 Published by INTERNATIONAL COMPUTERS LIMITED at OXFORD UNIVERSITY PRESS iCL The ICL Technical Journal is published twice a year by TECHniCRl International Computers Limited at Oxford University jouRnfli Press. Editor J. Howlett ICL House, Putney, London SW15 ISW, UK Editorial Board J. Howlett (Editor) F.F. Land H.M. Cropper (F International) (London School of Economics & D.W. Davies, FRS Political Science) G.E. Felton K.H. Macdonald M.D. Godfrey M R. Miller C.H.L. Goodman (British Telecom Research (Standard Telephone Laboratories) Laboratories and Warwick J.M. Pinkerton University) E.C.P. Portman All correspondence and papers to be considered for publication should be addressed to the Editor. The views expressed in the papers are those of the authors and do not necessarily represent ICL policy. 1987 subscription rates: annual subscription £32 UK, £40 rest of world, US $72 N. America; single issues £17 UK, £22 rest of world, US $38 N. America. Orders with remittances should be sent to the Journals Subscriptions Department, Oxford University Press, Walton Street, Oxford 0X2 6DP, UK. This publication is copyright under the Berne Convention and the Interna­ tional Copyright Convention. All rights reserved. Apart from any copying under the UK Copyright Act 1956, part 1, section 7, whereby a single copy of an article may be supplied, under certain conditions, for the purposes of research or private study, by a library of a class prescribed by the UK Board of Trade Regulations (Statutory Instruments 1957, No. 868), no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without the prior permission of the copyright owners.
    [Show full text]
  • Load Sharing in Distributed Computer Systems Tahir
    LOAD SHARING IN DISTRIBUTED COMPUTER SYSTEMS TAHIR M. AFZAL NEWCASTLE UNIVCRSITY LIBRARY '" ___ •• M _____••••• .. .. " .- .- .. - _." .-., . -.- .. ~-"'.--............. _.. - ........ -.......... -... _.. ... " .......... _---_ ... --·--··--~·;s L- '3~~q PhD Thesis The University of Newcastle upon Tyne Computing Laboratory August, 1987 ABSTRACT In this thesis the problem ofload sharing in distributed computer systems is investigated. Fundamental issues that need to be resolved in order to implement a load sharing scheme in a distributed system are identified and possible solutions suggested. A load sharing scheme has been designed and implemented on an existing Unix United system. The performance of this load sharing scheme is then measured for different types of programs. It is demonstrated that a load sharing scheme can be implemented on the Unix United systems using the existing mechanisms provided by the Newcastle Connection, and without making any significant changes to the existing software. It is concluded that under some circumstances a substantial improvement in the system performance can be obtained by the load sharing scheme. ACKNOWLEDGEMENTS I would like to thank Dr. Snow for his constructive advice in supervising this thesis. I am also very grateful to Professor Brian Randell for his invaluable comments on preliminary drafts of this thesis. Several colleagues in the Computing Laboratory helped me during my research. In particular I am thankful to Robert Stroud for his help in solving the problems related to the Newcastle Connection. I wish to thank Dr. Lindsay Marshall, Andy Linton and Steve Grimes for their technical help. I am grateful to Professor Peter Lee for his comments on the final draft of this thesis.
    [Show full text]
  • Perqflex Firmware
    AD A166 190 PIROFLEX FIMAKIUI ROYAL SIMALS AM *OARA ESTAILISIMN UALVERN (ENOLAMI I F CURRIE ET AL. DEC 85 NSE0501S 041IC-S-9S025 UNCLASSIFIED F/a 012 ut I II. r ..- 2I0 111I1I5 IIIIII III I 4,- i I/ ROYAL SIGNALS AND RADAR ESTABLISHMENT Report No 8581S Title: PerqFlex Firmware Authors: I F Currie, J M Foster and P W Edwards Date - December 1985 Summary This report describes the instruction set and general firmware architecture of the Flex computer as implemented on the ICL Perq workstation. Accession For NTIS GRA&I DTIC TAB Unannounced ' w Justification By___By Distribution/ Availability Codes Avail and/or 4,Dist Special Copyrlulit Controller 14RS0 London 1M IL PerqFlex Firmware Contents Introduction I Data in Flex 2 Program in Flex )3 Procedures 4 Exceptions 5 Storage allocation 6 Interrupts 7 External capabilities 8 Flex instruction set 9 Formats of data, blocks and exceptions Introduction This report describes the firmware architecture of the Flex computing system as implemented on the ICL Perq. This implementation is very similar to that described in RSRE Report 81009, ( Flex Firmware by -I Currie, Edwards and Foster) generally referred to as the Logica implementation. This is rather a misnomer, since although Logica built the hardware (to an RSRE design) on which it was implemented, Logica had nothing to do with the micro-coding or software construction of the Flex architecture. The differences between the Perq and Logica implementation arise mainly from the properties of the underlying hardware. In the Logica Flex, for example, each byte in main-store was in fact nine bits long rather than eight s the extra bits (the tag bits) were used to distinguish between pointers and non-pointers ie between capabilities and scalar data.
    [Show full text]