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Exploring CTOS@ -• EXPLORING Edna lIyin Miller, Jim Crook, and June Loy Exploring CTOS@ Edna [lyin Miller, Jim Crook, and June Loy it Prentice Hall, Englewood Cliffs, New Jersey 07632 Library of Congress Cataloging-in-Publication Data Explor1ng CTOS I Un1sys Corp. p. cm. Includes 1ndex. ISBN 0-13-297342-1 1. D1str1buted operat1ng systems (Computers) 2. CTOS. 1. Unlsys Corporat1on. CA76.76.063E954 1991 005.4'3--dc20 90-27131 CIP This book was written, edited, and composed using the CroS-based desktop publishing system, OFIS Document Designer. The system used was a CroS-based 386 workstateion with VGA graphics. The graphics were created in OFIS Graphics, then integrated into the cros Document Designer files. The printer used was an Apple LaserWriter~ Text is New Century Schoolbook. Helvetica is used for headings. Program listings are set in Courier. Cover Design: April Bishop Editing: Carol Collins Production Editing: Antoinette Kohn Illustrations: Jacqueline Mac Millan Page Design: Milena Martin-Arana II © 1991 by Prentice·Hall, Ino = A Division of Simon & Schuster - Englewood Cliffs, New Jersey 07632 The publisher offers discounts on this book when ordered in bulk quantities. For more information, write: Special SaleS/College Marketing Prentice Hall College Technical and Reference Division Englewood Cliffs, New Jersey 07632 All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission in writing from the publisher. Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 ISBN 0-13-297342-1 PRE:-.ITICE-HALL INTERNATIONAL (UK) LIMITED, London PR~:NTIC~:-HALL OF AUSTRALIA PTy. LIMITED, Sydney PRENTICE-HALL CANADA INC., Toronto PRENTICE-HALL HISPANOAMERICANA, S.A., Mexico PRENTICE-HALL OF INDIA PRIVATE LIMITED, New Delhi PRENTICE-HALL OF JAPAN, INC., Tokyo SIMO:-.l & SCHUSTER ASIA PTE. LTD., Singapore ElllTORA PRENTICE-HALL DO BRASIL, LTDA., Rio de Janeiro Contents Preface xiii Part 1. An Introduction to CTOS Chapter 1. CTOS In Brief ....... 3 The Working Model. 4 CTOS Support for the Model ..................... 4 A Message-Based Operating System .............. 5 A Simple Cluster LAN. 5 A Modular, Extensible System ...... 5 The Old Way. 6 A Building Blocks Approach . 7 Processes: the Building Blocks ................... 8 Process Scheduling ............................ 8 Messages: the Mortar . 9 The Roles of Interprocess Communication (IPC) . 11 The Role of the CTOS Kernel. 11 System Services. 11 Operating Across a Network ...................... 12 What Can You Do With This? . 13 What Does It Look Like? . 13 Chapter 2. Physical Systems ............................... 15 The X-Bus. 19 Cluster and TeleCluster ...... 19 Larger Networks ...... 22 Running MS-DOS Programs. 24 PC Emulator. 24 ClusterCard and ClusterShare . 24 Why CTOS Is What It Is. 25 iii Contents Chapter 3. Of History, Religion, and Marketing. ........ ..... 27 The First Direction. 28 Basic Decisions. 28 Networking From Day Two. 31 The Request Procedural Interface . 31 Changing Course........... ..... ....... ...... .... 32 The Early Religion. .. .. 33 More Office Applications . 35 Why the Accident Was a Happy One. 36 A Turning Point . 36 Multitasking for the End User ....................... 38 Horizons and Realities: The 80186 and 80286 Chips . 40 The DISTRIX experiment ........................... 42 First With the Most ............ 43 DOS Compatibility. .. .. 45 First With the Most Again: The 80386 Chip. 48 The Big Time . 48 CTOS/Open ...................................... 49 Religion and the Future ............................ 50 Part 2. CTOS and CTOS Applications Chapter 4. Thinking About Distributed Applications. 55 Distributed Applications. 56 Large Computers . 56 Personal Computers. 56 Issues In Creating Distributed Applications. 57 Distributing Applications Under eTaS. 59 Chapter 5. Timekeeper: A CTOS Application. ... .... .. ...... 61 A Look at Some Distributed Applications. 62 A Unique Application: Reporting Sports Results. 62 Interoffice Communication: eTOS Electronic Mail .... 64 Timekeeper: Our Distributed Application. 65 A Framework for the Design ........................ 65 The Design Environment ........................ 66 Steps Toward a Design. 67 Starting Simply . 67 Relating the Design to the Network . 68 User Inputs and Outputs. 68 Needed Functions ............................. 69 Division of Labor. 69 Using Existing Pieces. 71 Understanding Some Underpinnings . 72 w Contents Chapter 6. More About Messages . .. .. .. .. .. 73 CTOS Processes. 74 Process Creation .............................. 75 Process States . 75 The Scheduling Algorithm ....................... 76 Interrupt and Trap Handlers. 79 Processes In Other Kinds of Systems ................ 80 CTOS Programs. 80 Partitions . 82 Memory.......................................... 85 Interprocess Communication. 87 Other Environments . 87 CTaS IPC: Messages and Exchanges . 87 Messages . 87 The Exchange. 88 IPC Primitives. 90 Hiding the Mechanics: The Request/Response Model. 90 The Request Block. 91 Synchronous and Asynchronous Processing. 93 Requests Versus RPe. 94 A Few Other Mechanisms..... ...... ... ...... ... .. 95 Kernel Primitives. 95 System Common .............................. 95 Object Module Procedures. 96 Chapter 7. System Services ................................ 97 System Service/Client Interaction . 98 Partitions and User Numbers . 98 Request Codes.. .. 98 The Dynamics of Requests and Responses ......... 98 Pointer Aliases ........................... 99 Reaction of the System Service ......... 100 Connections . 101 Crossing the Network . 102 Agents ...................................... 103 Filters ........' . 106 Filters and Extensibility. 109 The Basic Structure of a System Service . 109 A Look Ahead. .. .. .. 110 v Contents Chapter 8. Input/Output Overview. 111 Device-Dependence and Device-Independence. 112 Hierarchies of eTOS 110 Tools. 113 Primitives: Device-Dependent . 114 Tools Built on Primitives. 115 Sequential Access Method . 115 Non-SAM Tools. .. 120 A eTOS 1/0 Road Map. 120 Video ....................................... 121 Keyboard and Mouse. 121 Data Storage ................................. 122 Communications ............,. 123 Printing . 124 Chapter 9. Video and Keyboard Options. 127 Video Frames and Attributes . 128 Frames...... ..... ................ ........... 128 Video Attributes ............................... 129 Types of Video Hardware . 129 Levels of Video Access ............................ 129 Using Video Byte Streams . 131 Using VDM and VAM ...... ... ....... ........... 131 Initializing the Video Subsystem. 131 Writing to the Video. 132 Keyboard Input Tools. 133 Keyboard Byte Streams . 133 Keyboard Management ......................... 134 System Input Process. 135 Mouse Services ............................... 135 Forms Package . 136 Graphical User Interface. 136 The eTOS GUI Solution.... ... ....... ........... 137 Presentation Manager. 137 Extensible Virtual Toolkit (XVT) .............. 137 Context Manager's Role . 139 Later Additions ........................... 139 Some New Underpinnings ............ 139 Chapter 10. Data Storage and Access...... ....... ... .... .... 141 Disk Storage and the File System . 142 File Specifications. 142 Disk Structures and Reliability .................... 143 System Image. 144 Allocation Bit Map. 144 vi Contents Master File Directory. 145 File Header Block . 146 Structures in Memory ...................... 146.
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