CEKN 91-05 14 May 1991 ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 1990 CERN SCHOOL OF COMPUTING Ysermonde, Belgium 2-15 September 1990 PROCEEDINGS GEMEVA 1991 © Copyright CERN, Genève, 1991 Propriété littéraire et scientifique réservée Literary and scientific copyright-i r^-tw^d în pûui tous les pays du mund», Ge document ne nil cnuutrie* at the world. This report, or peut être reproduit ou traduit en tout DU en any part of it, may not be reprinted or trans­ partie sans l'autorisation écrite du Directeur lated wiLliHxit written permission of the copy­ littéral du CERN, titulaire du droit d'auteur. right holder, tile Director-General of CERN, Dans les cas appropriés, et s'il s'a.{pt d'utiliser However, permission will be freely granted for le docu un- il l & îles fins lion commerciales, cet te appropriate non-commercial use autorisation sera volontiers accordée- If any patentable invention or registrable Le OEKN ne revendique pas In propriété des design is described in the report. CERN makes inventions brevelables et dosum ou modèles no claim t« properly rights in it but oirer» ft susceptible* de dépôt qui pour™enl être for the free use of research institutions, man­ décrits dans le présent document; ceux-ci peu­ ufacturers and others. CERN, however, may vent être libn-ini-iil utilisés par les institut» de oppose any attempt by n user to claim any H'du-! du-, las industriel» et autre* intéressés. proprietary Or patent rights in such invention* Cependant, l« CERN se réserve le droïi de or designs as may be deMnrilwd in the present s'opposer & toute revendication qu'un Usager document. pointait faire de la propriété scientjrurue ou industrielle de toute invention si tout dessin ou modèle décrits dans le présent document- ISSN (KM-289* ISBN 92-90S3-Q36-D CERN 91-05 14 May 1991 ORGANISATION EUROPEENNE POUR LA RECHERCHE NUCLÉAIRE CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 1990 CERN SCHOOL OF COMPUTING Ysermonde, Belgium 2-15 September 1990 PROCEEDINGS GENEVA 1991 CERN Service d'information scientifique RD/819 2500 mai 1991 ABSTRACT These Proceedings contain written versions of lectures delivered at the 1990 CERN School of Computing, covering a variety of topics. Computer networks are treated in three papers: standards in computer networking; evolution of local and metropolitan area networks; asynchronous transfer mode, the solution for broadband ISDN, Data acquisition and analysis are the topic of papers on: data acquisition using MODEL software; graphical event analysis. Two papers in the field of signal processing treat digital image processing and the use of digital signal processors in HEP. Another paper reviews the present state of digital optical computing. Operating systems and prograrnrning discipline are covered in two papers: UNIX, evolution towards distributed systems; new developments in program verification. Three papers treat miscella­ neous topics: computer security within the CERN environment; numerical simulation in fluid mechanics; fractals. An introduction to transputers and Occam gives an account of the tutorial lectures given at the School. in IV PREFACE Forty-two students from thirteen countries participated in the thirteenth CERN School of Com­ puting, whieh was held in September 1990 in Ysennonde, Nieuwpoort, Belgium. The Sehool was organized in collaboration with the Inter-University Institute for High Energy Physics in Brussels. We heartily thank Professors J. Lemonne and J. Sacton for their active participa­ tion in organizing the Sehool. We extend our thanks to their collaborators Mrs. Alluyn, Paul Van Binst and Rosette van den Broeke for their assistance. We are grateful to the Belgian "Institut Inter-Universitaire des Scienees Nucléaires* for its financial contribution. We thank particularly Professor P. Levaux for his interest in this School. The participants highly appreciated the lecture programme, which covered a variety of topics, as these Proceedings show. We were happy to have opening lectures by Professor J, Lemonne and by Dr. D. Talbot of the EEC. We are very grateful to them and to all the other lecturers and the Advisory Committee for their efforts, resulting in a very interesting programme. The tutorial lectures and the practical sessions on transputers and Oceam were received with the same enthusiasm as last year. We are grateful to Bob Dobinson and Ian Willers for having arranged this very attractive part of the programme. We warmly thank Rekha Gupta, Henrik Kristensen, Andy Jackson and Wei Zhao Lu for their assistance during the afternoon sessions. The practieal sessions would not have been possible without the collaboration of a number of firms, who provided equipment and software. Hewlett Paekard is sineerely thanked for lending twelve Apollo workstations, which were specially flown in from the USA for this School. We are very grate­ ful to Mr. R. O'Brien who arranged for this. Inmos Ltd. and the Southampton Transputer Centre are thanked for their loan of transputer boards and for releasing Andy Jackson from his normal duties. Digital graciously provided again terminals and a micro VAX for the e-mail facilities, following in this a habit of several years. Our sincere thanks go to Mr. M. van der Straeten for arranging this and to Car- ola Clavi, who assisted in demonstrating graphics packages. Mrs. Gerda Moeijaert and Mr. de Smet did everything possible to make our stay at Ysermonde a memorable one. Our sincere thanks are due to them and to all of their staff. On the Sunday an excursion was organized to Bruges. Our guide, Dirk van Tieghem of the Uni­ versity of Ghent and the "Westvlaamse Gidsenkring* transformed this visit into an unforgettable cultur­ al event. We wish to thank him for his most interesting explanations. As usual, it is a pleasure to thank Ingrid Bamett for her efficient work and dedication. C. Verkerk Editor v ADVISORY COMMITTEE B. CARPENTER, CERN, Geneva, Switzerland R.F. CHURCHHOUSE, University of Wales, Cardiff, U.K. (Chairman) A. DANTHINE, Université de Liège, Belgium R.W. DOBINSON, CERN, Geneva, Switzerland J. LEMONNE, Inter-University Institute, Brussels, Belgium J. SACTON, Inter-University Institute, Brussels, Belgium J.J. THRESHER, CERN, Geneva, Switzerland A. VAN DAM, Brown University, Providence, U.S.A. C. VERKERK, CERN, Geneva, Switzerland (Scientific Secretary) D.O. WILLIAMS, CERN, Geneva, Switzerland P. ZANELLA, CERN, Geneva, Switzerland I. BARNETT, CERN, Geneva, Switzerland (School Secretary) VI CONTENTS Preface V Advisory Committee VI On LANs and MANs: an evolution from Mbil/s lo Gbit/s, P. Zafiroputo 1 ATM: solution for B-1SDN, M. De Prycker 9 Standards in computer networking, P. Van Binst 47 An introduction to transputers and OCCAM, R.W. Dobinson, D.RJV. Jeffery and I.M. Witters 52 New developments in program verification, P. Wolper 91 Unix: évolution towards distributed systems, E, Milgrom 97 Computer security within the CERN environment, D.ll, Lord 127 Numerical simulation in fluid mechanics, II. OcrieiJr. 131 Digital optical computing, S.D. Smith 167 Introduction to digital image processing, M. Kuni 211 Digital signal processing in high energy physics, D. Croselto 263 Data acquisition using the 'MODEL' software, P. Vande Vyvre 293 Graphical event analysis, D. Bertrand 316 Simulation of natural fractals by IFS, DLA and L-string systems, R.F. Churchouse 339 List of participants 351 vu ON LANs AND MANs: AN EVOLUTION FROM Mbit/s TO Gbit/s*) Pitro Zafiropulo IBM Research Division, Zurich Research Laboratory, 8803 Ruschlikon, Switzerland This paper focuses on the trend towards ever higher may well require data rates in the many hundreds of speeds in shared-medium based networks such as LANs Mbit/s to even the gigabit per second (Gbit/s) speed range. and MANs. The token passing ring protocol is introduced Attention is also being focused on motion graphics such as with emphasis on its performance and simplicity advan­ visualization and animation which require even greater tages over the token passing bus approach. The issues of bandwidths when operated interactively over supercom­ scaling up the token ring principle to higher speeds is con­ puter distribution networks. sidered with the help of the Early Token Release and FDDI More graphics-based applications have yet to be protocols. Although networks based on token passing invented, but when one considers the potential of motion operate efficiently at speeds up to 100 Mbit/s it is shown graphics as a new form of man/machine interface' then it that they exhibit inherent performance limitations in the is time to consider LANs and MANs for Gbit/s and near Gbit/s speed range. This leads one to consider the advan­ Gbit/s speeds. The seriousness of this trend is reflected tages of protocols based on slot reservation at very high by the increased activity in such networks.2"6 This develop­ speeds. An example of this is the Distributed Queue Dual ment may well be accelerated by the forthcoming 0.8 Bus (DQDB) MAN proposal. Unpredictable behavior and Gbit/s high-speed channel standard HSC (newly renamed lack of fairness, however, make it inadequate at very high to High-Performance Peripheral Interface, HPPI) proposed speeds so that other approaches must be considered. by ANSI X3T9.3.7 This standard developed for transporting visualization payload from a supercomputer to a work­ 1. Introduction station has the potential of becoming an attractive attach­ ment to Gbit/s networks. Local Area Networks (LANs) are being used today in This paper focuses on the trend towards ever higher myriad different applications spanning office and industrial speeds in networks based on shared media access caused environments. Many different LAN networks support these by these applications, a situation which may be com­ applications adequately at speeds ranging from 1 to 20 pounded in the future. The token passing ring protocol is Mbit/s.