DOCSLIB.ORG

Biography Per Brinch Hansen

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Biography Per Brinch Hansen Biographies Thomas Haigh, Editor University of Pennsylvania Biography used the simplest possible techniques to solve an unfa- miliar problem of modest size. Per Brinch Hansen The RC 4000 multiprogramming system introduced the novel idea of a system kernel for parallel processes and message communication that can be extended with a variety of operating systems.2 Brinch Hansen left the computer industry in 1970 and became a university researcher in the US. The implementation techniques of operating systems were reasonably well understood in the late sixties. But most systems were too large and poorly described to be studied in detail. While Edsger Dijkstra had clarified fun- Per Brinch Hansen was born 13 November 1938, in damental aspects of process synchronization, most of the Copenhagen, Denmark. He is a pioneer in the develop- literature on operating systems emphasized implementa- ment of operating system principles and parallel pro- tion details of particular systems rather than general con- gramming languages. cepts. The terminology was unsystematic and incomplete. At the time there really were no suitable textbooks on Significant work operating systems. Universities were therefore unable to Written over a period of more than 30 years, Brinch teach core courses on the subject. In 1970 Alan Perlis Hansen’s technical papers and textbooks describe a relent- invited Brinch Hansen to spend a year at Carnegie Mellon less search for simplicity exemplified by the RC 4000 mul- University where he wrote the first comprehensive text- tiprogramming system; the Solo operating system; the book on the principles of operating systems, Operating monitor notation for modular parallel programming; the System Principles.3 parallel programming languages Concurrent Pascal, Of the process of understanding operating systems he Edison, Joyce, and SuperPascal; and his scientific programs said: for parallel architectures. Throughout his career, Brinch Hansen attempted to recognize the essence of complex While writing the book I reached the conclusion that operat- software problems and express them in terms of a small ing systems are not radically different from other programs. number of abstract concepts. The technical ideas he rec- They are just large programs based on the principles of a more ognized are now standard material in textbooks on oper- fundamental subject: parallel programming. ating systems and parallel programming. His scientific Starting from a concise definition of the purpose of an oper- work can be divided into three phases: operating system ating system, I divided the subject into five major areas. First, principles (1966–1972), parallel programming languages I presented the principles of parallel programming as the (1972–1988), and computational science (1988–1998). In essence of operating systems. Then I described processor man- recent years, he has devoted increasing energy toward agement, memory management, scheduling algorithms, and documenting the historical origins of modern operating resource protection as techniques for implementing parallel systems and concurrent programming concepts. processes. Brinch Hansen studied electrical engineering at the I defined operating system concepts by algorithms written Technical University of Denmark. After graduating in in Pascal extended with an (unimplemented) notation for 1963 he joined the Danish computer company structured multiprogramming. The book includes a concise Regnecentralen. There he was a member of a Cobol com- vocabulary of operating system terminology, which is used piler group headed by Peter Naur and Jorn Jensen. He dis- consistently throughout the text.3 covered that writing is a rigorous test of simplicity: “It is just not possible to write convincingly about ideas that The combined work of Dijkstra, Tony Hoare, and cannot be understood.”1 At Regnecentralen he was Brinch Hansen on programming notation for operating responsible for the architecture and software of the RC system concepts led to the initial development of paral- 4000 minicomputer. The RC 4000 real-time control sys- lel programming languages. It began in 1971 with Hoare’s tem was his first experience with multiprogramming and notation for a conditional critical region that delays one semaphores (1967). The project succeeded because they or more processes until a Boolean expression is true. 80 IEEE Annals of the History of Computing Published by the IEEE Computer Society 1058-6180/03/$17.00 © 2003 IEEE Unfortunately, this elegant idea is inefficient processors with shared memory toward multi- because it requires periodic reevaluation of the computers with distributed memory. For micro- expression as long as it is false. One of Brinch computer networks, Brinch Hansen proposed a Hansen’s first papers on programming language combination of processes and monitors called concepts proposed an (equally inefficient) vari- distributed processes, which communicate by ant of conditional critical regions for priority means of synchronized “remote procedure scheduling. A more original idea was his intro- calls.”7 duction of scheduling queues, which eliminat- After Concurrent Pascal, Brinch Hansen ed superfluous evaluation (but complicated the designed the parallel programming languages, programming somewhat).4 Edison and Joyce, to experiment with Hoare’s Dijkstra, Hoare, and Brinch Hansen suggest- concepts of conditional critical regions and ed another parallel programming concept in synchronous message communication, 1971: the monitor, which combines synchro- respectively.8,9 nization procedures with the shared variables At the end of the preface to his collection upon which they operate. Brinch Hansen’s oper- of classic papers,1 Brinch Hansen said of his ating system book3 introduced a programming activities: notation for monitors (shared classes), based on the class concept of Simula 67. Somewhat later, In the 1990s the programming problems of oper- Hoare published a similar notation for monitors. ating systems have surfaced again in parallel sci- His proposal included a variant of Brinch entific computing: there is a serious need for Hansen’s scheduling queues (“conditions”). machine-independent programming languages By the fall of 1972 Brinch Hansen was and algorithms. To understand this challenge I already committed to the goal of developing a spent five years writing portable multicomputer parallel programming language with a modu- algorithms for typical problems in science and lar (“object-oriented”) notation for processes engineering. My book, Studies in Computational and monitors. At the California Institute of Science,10 describes this work. Technology he defined the programming lan- guage Concurrent Pascal, which supports mon- In 2002, the IEEE Computer Society award- itors and parallel processes for implementation ed Brinch Hansen its IEEE Computer Pioneer of modular operating systems. Because syn- Award for his accomplishments in operating chronization errors can be extremely difficult systems and concurrent programming. to locate by program testing, Concurrent Pascal Fittingly, this recognition came after several was designed to permit the detection of such years of work on his part to document histori- errors during compilation. With the help of a cal developments in these areas, and to cele- couple of students, a portable implementation brate and illuminate the accomplishments of of the language was running on a PDP-11 mini- his fellow pioneers. His efforts in this area have computer at the end of 1974. Concurrent already produced two edited volumes, one Pascal had obvious limitations by today’s stan- focused on classic operating systems11 and the dards. But, in 1975, it laid the foundation for other on the major breakthroughs in concur- the development of programming languages rent programming.12 Brinch Hansen recently with abstract concepts for parallelism. joined the editorial board of the IEEE Annals of Brinch Hansen used Concurrent Pascal to the History of Computing, where we hope to ben- program the portable operating system Solo as efit from his expertise and enthusiasm. a realistic test of the new programming lan- guage. The most significant contribution of Solo Quotations was undoubtedly that the program text was “Writing is a rigorous test of simplicity: It is short enough to be published in its entirety in just not possible to write convincingly about a computer journal.5 The portable implementa- ideas that cannot be understood.”1 tion of Concurrent Pascal and Solo was highly successful in spreading the software to almost “Programming is the art of writing essays in 200 installations worldwide. The time was now crystal clear prose and making them ripe for a book about the principles of abstract executable.”6 parallel programming, and so he produced The Architecture of Concurrent Programs6 while at the “Although the practical demands of soft- University of Southern California. The book ware design make simplicity essential, a more includes the complete text of three model oper- profound reason is to be found in the nature of ating systems written in Concurrent Pascal. creative work. The joy of discovery and the Technology was now moving from multi- pleasure of making something work are the January–March 2003 81 Biographies Biographical bibliography Background of Per Brinch Hansen P. Brinch Hansen, “The Programmer as a Young Dog,” Education: Brinch Hansen earned an MS in electrical engineer- The Search for Simplicity: Essays in Parallel ing in 1963 from Technical University of Denmark. Professional
Load more

Recommended publications
  • Concurrent Programming Introduction
    v1.0 20130407 Programmazione Avanzata e Paradigmi Ingegneria e Scienze Informatiche - UNIBO a.a 2013/2014 Lecturer: Alessandro Ricci [module 2.1] CONCURRENT PROGRAMMING INTRODUCTION PAP LM - ISI - Cesena - UNIBO !1 SUMMARY • Concurrent programming – motivations: HW evolution – basic jargon • processes interaction, cooperation, competition, • mutual exclusion, synchronization • problems: deadlocks, starvation, livelocks • A little bit of history – Dijkstra, Hoare, Brinch-Hansen • Concurrent languages, mechanisms, abstractions – overview PAP LM - ISI - Cesena - UNIBO Introduction !2 CONCURRENCY AND CONCURRENT SYSTEMS • Concurrency as a main concept of many domains and systems – operating systems, multi-threaded and multi-process programs, distributed systems, control systems, real-time systems,... • General definitions – “In computer science, concurrency is a property of systems in which several computational processes are executing at the same time, and potentially interacting with each other.” [ROS-97] – “Concurrency is concerned with the fundamental aspects of systems of multiple, simultaneously active computing agents, that interact with one another” [CLE-96] • Common aspects – systems with multiple activities or processes whose execution overlaps in time – activities can have some kind of dependencies, therefore can interact PAP LM - ISI - Cesena - UNIBO Introduction !3 CONCURRENT PROGRAMMING • Concurrent programming – building programs in which multiple computational activities overlap in time and typically interact in some way • Concurrent program – finite set of sequential programs that can be executed in parallel, i.e. overlapped in time • a sequential program specifies sequential execution of a list of statements • the execution of a sequential program is called process • a concurrent program specifies two or more sequential programs that may be executed concurrently as parallel processes – the execution of a concurrent program is called concurrent computation or elaboration PAP LM - ISI - Cesena - UNIBO Introduction !4 CONCURRENT PROGRAMMING VS.
    [Show full text]
  • The Programming Language Concurrent Pascal
    IEEE TRANSACTIONS ON SOFTWARE ENGINEERING, VOL. SE-I, No.2, JUNE 1975 199 The Programming Language Concurrent Pascal PER BRINCH HANSEN Abstract-The paper describes a new programming language Disk buffer for structured programming of computer operating systems. It e.lt­ tends the sequential programming language Pascal with concurx:~t programming tools called processes and monitors. Section I eltplains these concepts informally by means of pictures illustrating a hier­ archical design of a simple spooling system. Section II uses the same enmple to introduce the language notation. The main contribu~on of Concurrent Pascal is to extend the monitor concept with an .ex­ Producer process Consumer process plicit hierarchy Of access' rights to shared data structures that can Fig. 1. Process communication. be stated in the program text and checked by a compiler. Index Terms-Abstract data types, access rights, classes, con­ current processes, concurrent programming languages, hierarchical operating systems, monitors, scheduling, structured multiprogram­ ming. Access rights Private data Sequential 1. THE PURPOSE OF CONCURRENT PASCAL program A. Background Fig. 2. Process. INCE 1972 I have been working on a new programming .. language for structured programming of computer S The next picture shows a process component in more operating systems. This language is called Concurrent detail (Fig. 2). Pascal. It extends the sequential programming language A process consists of a private data structure and a Pascal with concurrent programming tools called processes sequential program that can operate on the data. One and monitors [1J-[3]' process cannot operate on the private data of another This is an informal description of Concurrent Pascal.
    [Show full text]
  • The Programmer As a Young Dog
    The Programmer as a Young Dog (1976) This autobiographical sketch describes the beginning of the author’s career at the Danish computer company Regnecentralen from 1963 to 1970. (The title is inspired by James Joyce’s “A Portrait of the Artist as a Young Man” and Dylan Thomas’s “Portrait of the Artist as a Young Dog.”) After three years in Regnecentralen’s compiler group, the author got the chance to design the architecture of the RC 4000 computer. In 1967, he became Head of the Software Development group that designed the RC 4000 multiprogramming system. The article was written in memory of Niels Ivar Bech, the dynamic director of Regnecentralen, who inspired a generation of young Danes to make unique contributions to computing. I came to Regnecentralen in 1963 to work with Peter Naur and Jrn Jensen. The two of them worked so closely together that they hardly needed to say anything to solve a problem. I remember a discussion where Peter was writing something on the blackboard, when Jrn suddenly said “but Peter ...” and immediately was interrupted with the reply “yes, of course, Jrn.” I swear that nothing else was said. It made quite an impression on me, especially since I didn’t even know what the discussion was about in the rst place. After a two-year apprenticeship as a systems programmer, I wanted to travel abroad and work for IBM in Winchester in Southern England. At that time Henning Isaksson was planning to build a process control computer for Haldor Topse, Ltd. Henning had asked Niels Ivar Bech for a systems programmer for quite some time.
    [Show full text]
  • Concurrent Pascal
    LIBP.ARY CLEARANCE 1. (a) I give my permission for my thesis, entitled .....~D.~~ r.r-.m1 .... P.C?.~~.: .. .) Q?y).~-tJ.\.1Ati~0.. A,:&. U~oJe- .................................................................... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. to be made available to readers in the Library under the conditions determined by the Librarian. (b) I agree to my thesis, if asked for by another institution, being sent away on temporary loan under conditions determined by the Librarian. (e) I also agree that oy thesis may be copied for Library use. 2. I do not wish m . .. .. .. .. .. .. ......................................... ...................~--- ~-........................ .. .. .. .. .. .. ~ ................... ~- ...................... •. '" -, to be made available to re~~,or to be sent ~ll.er ins-ti-tut.ions without my written consent withiri'--the next two years~ Signed .. 1?~~-............... Date ... ?!.? I 9./.$~.................. Strike out the se»tence or phrase which does not apply. The Library Massey University Palmerston North, N.Z. The copyright of this thesis belongs to the author. Readers must ~ign their name in the space below to show that they recognise this. They are asked to add their permanent address. Name and Address Date ................................................................................. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ••••••••••••••o•••••••••••• .. •••••••••••••••••••••••••••••••••••••••••••••••••••• ................................................................................
    [Show full text]
  • Part Iii Harnessing Parallelism
    PART III HARNESSING PARALLELISM The primary impetus behind the study of parallel programming, or concurrent programming as some would call it, was the necessity to write operating systems. While the first computers were simple enough to be considered sequential in nature, the advent of faster central processing units and the accompanying discrepancy in speed between the central processor and periph­ eral devices forced the consideration of possible concurrent activity of these mechanisms. The operating system was asked to control concurrent activity, and to control it in such a way that concurrent activity was maximized This desire for concurrent activity resulted in machine features such as the channel and the interrupt-the mechanism by which termination of an I/O activity is signaled The main problem with the interrupt, as far as the operating system designer was concerned, was its inherent unpredictability. Not knowing exactly when an interrupt could occur, the operating system had to be designed to expect an interrupt at any time. With the advent of multiprogramming and interactive, on-line processing, it became clear that the original motivation for parallelism-the control and exploitation of concurrent I/O-was only a special case, and some fundamen­ tal concepts began to emerge for study and use in more general parallel programming situations. Thus emerged the general idea of a set of processes executing concurrently, with the need for synchronization and mutual exclu­ sion (with respect to time) of some of their activities. The past 10-15 years have seen an enormous amount of activity in studying the general problem, a very small part of which is presented here.
    [Show full text]
  • Pascal Versus C : a Subjective Comparison
    PROCEEDINGS OF THE SYMPOSIUM ON LANGUAGE DESIGN AND PROGRAMMING METHODOLOGY SYDNEY, 10-11 SEPTEMBER~ 1979 PASCAL VERSUS C A SUBJECTIVE COMPARISON Prabhaker Mateti Department of Computer Science University of Melbourne ABSTRACT The two programming languages Pascal and C are subjectively compared. While the two languages have comparable data and control structures, the program structure of C appears superior. However, C has many potentially dangerous features, and requires great caution from its programmers. Other psychological effects that the various structures in these languages have on the process of programming are also conjectured. "At first sight, the idea of any rules or principles being superimposed on the creative mind seems more likely to hinder than to help, but this is really quite untrue in practice. Disciplined thinking focusses inspiration rather than blinkers it." - G. L. Glegg, The Design of Design. I Introduction Pascal has become one of the most widely accepted languages for the teaching of programming. It is also one of the most thoroughly studied languages. Several large programs have been written in Pascal and its derivatives. The programming language C has gained much prominence in recent years. The successful Unix operating system and most of its associated software are written in C. This paper confines itself to a subjective comparison of the two languages, and conjectures about the effect various structures of the languages have on the way one programs. While we do occasionally refer to the various extensions and compilers of the languages, the comparison is between the languages as they are now, and in the context of general programming.
    [Show full text]
  • A Programmer's Story. the Life of a Computer Pioneer
    A PROGRAMMER’S STORY The Life of a Computer Pioneer PER BRINCH HANSEN FOR CHARLES HAYDEN Copyright c 2004 by Per Brinch Hansen. All rights reserved. Per Brinch Hansen 5070 Pine Valley Drive, Fayetteville, NY 13066, USA CONTENTS Acknowledgments v 1 Learning to Read and Write 1938–57 1 Nobody ever writes two books – My parents – Hitler occupies Denmark – Talking in kindergarten – A visionary teacher – The class newspaper – “The topic” – An elite high school – Variety of teachers – Chemical experiments – Playing tennis with a champion – Listening to jazz – “Ulysses” and other novels. 2 Choosing a Career 1957–63 17 Advice from a professor – Technical University of Denmark – rsted’s inuence – Distant professors – Easter brew – Fired for being late – International exchange student – Masers and lasers – Radio talk — Graduation trip to Yugoslavia – An attractive tourist guide – Master of Science – Professional goals. 3 Learning from the Masters 1963–66 35 Regnecentralen – Algol 60 – Peter Naur and Jrn Jensen – Dask and Gier Algol – The mysterious Cobol 61 report – I join the compiler group – Playing roulette at Marienlyst resort – Jump- starting Siemens Cobol at Mogenstrup Inn – Negotiating salary – Compiler testing in Munich – Naur and Dijkstra smile in Stock- holm – The Cobol compiler is nished – Milena and I are married in Slovenia. 4 Young Man in a Hurr 1966–70 59 Naur’s vision of datalogy – Architect of the RC 4000 computer – Programming a real-time system – Working with Henning Isaks- son, Peter Kraft, and Charles Simonyi – Edsger Dijkstra’s inu- ence – Head of software development – Risking my future at Hotel Marina – The RC 4000 multiprogramming system – I meet Edsger Dijkstra, Niklaus Wirth, and Tony Hoare – The genius of Niels Ivar Bech.
    [Show full text]
  • Virtual Organization Clusters: Self-Provisioned Clouds on the Grid Michael Murphy Clemson University, [email protected]
    Clemson University TigerPrints All Dissertations Dissertations 5-2010 Virtual Organization Clusters: Self-Provisioned Clouds on the Grid Michael Murphy Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Part of the Computer Sciences Commons Recommended Citation Murphy, Michael, "Virtual Organization Clusters: Self-Provisioned Clouds on the Grid" (2010). All Dissertations. 511. https://tigerprints.clemson.edu/all_dissertations/511 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Virtual Organization Clusters: Self-Provisioned Clouds on the Grid A Dissertation Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Computer Science by Michael A. Murphy May 2010 Accepted by: Dr. Sebastien Goasguen, Committee Chair Dr. Jim Martin Dr. Walt Ligon Dr. Robert Geist Abstract Virtual Organization Clusters (VOCs) provide a novel architecture for overlaying dedicated cluster systems on existing grid infrastructures. VOCs provide customized, homogeneous execution environments on a per-Virtual Organization basis, without the cost of physical cluster construction or the overhead of per-job containers. Administrative access and overlay network capabilities are granted to Virtual Organizations (VOs) that choose to implement VOC technology, while the system remains completely transparent to end users and non-participating VOs. Unlike alternative systems that require explicit leases, VOCs are autonomically self-provisioned according to configurable usage policies. As a grid computing architecture, VOCs are designed to be technology agnostic and are implementable by any combination of software and services that follows the Virtual Organization Cluster Model.
    [Show full text]
  • Downloading from Naur's Website: 19
    1 2017.04.16 Accepted for publication in Nuncius Hamburgensis, Band 20. Preprint of invited paper for Gudrun Wolfschmidt's book: Vom Abakus zum Computer - Begleitbuch zur Ausstellung "Geschichte der Rechentechnik", 2015-2019 GIER: A Danish computer from 1961 with a role in the modern revolution of astronomy By Erik Høg, lektor emeritus, Niels Bohr Institute, Copenhagen Abstract: A Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. A GIER was installed at the Hamburg Observatory in 1964 where it was used to implement the entirely new method for the meas- urement of stellar positions by means of a meridian circle, then the fundamental instrument of as- trometry. An expedition to Perth in Western Australia with the instrument and the computer was a suc- cess. This method was also implemented in space in the first ever astrometric satellite Hipparcos launched by ESA in 1989. The Hipparcos results published in 1997 revolutionized astrometry with an impact in all branches of astronomy from the solar system and stellar structure to cosmic distances and the dynamics of the Milky Way. In turn, the results paved the way for a successor, the one million times more powerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a Gaia suc- cessor in twenty years are making progress. Zusammenfassung: Eine elektronische Rechenmaschine, GIER, von 1961 aus Dänischer Herkunft spielte eine vitale Rolle bei der Entwiklung einer neuen astrometrischen Messmethode.
    [Show full text]
  • A Secure Computing Platform for Building Automation Using Microkernel-Based Operating Systems Xiaolong Wang University of South Florida, [email protected]
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School November 2018 A Secure Computing Platform for Building Automation Using Microkernel-based Operating Systems Xiaolong Wang University of South Florida, [email protected] Follow this and additional works at: https://scholarcommons.usf.edu/etd Part of the Computer Sciences Commons Scholar Commons Citation Wang, Xiaolong, "A Secure Computing Platform for Building Automation Using Microkernel-based Operating Systems" (2018). Graduate Theses and Dissertations. https://scholarcommons.usf.edu/etd/7589 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. A Secure Computing Platform for Building Automation Using Microkernel-based Operating Systems by Xiaolong Wang A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Science and Engineering Department of Computer Science and Engineering College of Engineering University of South Florida Major Professor: Xinming Ou, Ph.D. Jarred Ligatti, Ph.D. Srinivas Katkoori, Ph.D. Nasir Ghani, Ph.D. Siva Raj Rajagopalan, Ph.D. Date of Approval: October 26, 2018 Keywords: System Security, Embedded System, Internet of Things, Cyber-Physical Systems Copyright © 2018, Xiaolong Wang DEDICATION In loving memory of my father, to my beloved, Blanka, and my family. Thank you for your love and support. ACKNOWLEDGMENTS First and foremost, I would like to thank my advisor, Dr. Xinming Ou for his guidance, encouragement, and unreserved support throughout my PhD journey.
    [Show full text]
  • BACI Pascal Compiler User Guide
    USER'S GUIDE BACI Pascal Compiler and Concurrent PCODE Interpreter Bill Bynum/Tracy Camp College of William and Mary/Colorado School of Mines July 14, 2003 BACI Pascal Compiler User's Guide 1 Contents 1 Introduction 2 2 Pascal Compiler Syntax 2 3 Concurrency Constructs 4 3.1 COBEGIN—COEND . 4 3.2 Semaphores . 4 3.2.1 Initializing a Semaphore . 4 3.2.2 P (or WAIT) and V (or SIGNAL) Procedures . 5 3.2.3 Examples of Semaphore Usage . 6 3.3 Monitors . 7 3.3.1 Condition Variables . 7 3.3.2 WAITC and SIGNALC Procedures . 7 3.3.3 Immediate Resumption Requirement . 8 3.3.4 An Example of a Monitor . 8 3.4 Other Concurrency Constructs . 8 3.4.1 ATOMIC Keyword . 9 3.4.2 PROCEDURE suspend; . 9 3.4.3 PROCEDURE revive( process number : INTEGER); . 9 3.4.4 FUNCTION which proc : INTEGER; . 9 3.4.5 FUNCTION random( range : INTEGER ): INTEGER; . 9 4 Built-in String Handling Functions 10 4.1 PROCEDURE stringCopy(dest : STRING; src : STRING); . 10 4.2 PROCEDURE stringConcat(dest : STRING; src : STRING); . 10 4.3 FUNCTION stringCompare(x : STRING; y : STRING): INTEGER; . 10 4.4 FUNCTION stringLength(x : STRING): INTEGER; . 10 4.5 FUNCTION sscanf(x : STRING; fmt : RAWSTRING ; ...): INTEGER; . 10 4.6 PROCEDURE sprintf(x : STRING; x, fmt : RAWSTRING,...); . 11 5 Using the BACI Pascal Compiler and PCODE Interpreter 11 6 Sample program and output 12 BACI Pascal Compiler User's Guide 2 1 Introduction The purpose of this document is to provide a brief description of the BACI Pascal Compiler and Concur- rent PCODE Interpreter programs and a description of how to use them.
    [Show full text]
  • Kernel Operating System
    International Journal of Advanced Technology in Engineering and Science www.ijates.com Volume No.02, Special Issue No. 01, September 2014 ISSN (online): 2348 – 7550 KERNEL OPERATING SYSTEM Manjeet Saini1, Abhishek Jain2, Ashish Chauhan3 Department Of Computer Science And Engineering, Dronacharya College Of Engineering Khentawas, Farrukh Nagar, Gurgaon, Haryana, (India) ABSTRACT The central module of an operating system (OS) is the Kernel. It is the part of the operating system that loads first, and it remains in main memory. It is necessary for the kernel to be very small while still providing all the essential services needed by other parts of the OS because it stays in the memory. To prevent kernel code from being overwritten by programs or other parts of the operating system it is loaded into a protected area of memory. The presence of an operating system kernel is not a necessity to run a computer. Directly loading and executing the programs on the "bare metal" machine is possible, provided that the program authors are willing to do without any OS support or hardware abstraction. Many video game consoles and embedded systems still constitute the “bare metal” approach. But in general, newer systems use kernels and operating systems. Keywords: Scalability, Multicore Processors, Message Passing I. INTRODUCTION In computing, the kernel is a computer program that manages input/output requests from software, and translates them into data processing instructions for the central processing unit and other electronic components of a computer. When a computer program (in this context called a process) makes requests of the kernel, the request is called a system call.
    [Show full text]