-R127 586 LABORATORY FOR COMPUTER SCIENCE'PROGRESS REPORT ig JULY 1/3 1986-JUNE 1981(U) MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR COMPUTER SCIENCE. M L DERTOUZOS 01 APR 82 UNCLASSIFIEDEhE0 LCS-PR-i8 00 N9014-75-C-8661 0 0 0 1iEF/G 9/2 N EhhhhhhhhhhhhE EhhhhhhhhhhhhE EhhhhhhhmhhhhE EhhhhhhhhhhhhI EhhhhhhohmhhhE ".2 111.0 t IL8125 IL .2 j'Ill-'liii 111.25 111. ~lI MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF SIANDARDS-1963-A a-, MASSACHUSETTS LABORATORY FOR INSTITUTE OF COMPUTER SCIENCE TECHNOLOGY PROGRESS REPORT 18 July 1980- June 1981 1i MAY 2 1.83 CL- Prepared for the Defense Advanced Research Projects Agency 545 TECHNOLOGY SQUARE. CAMBRIDGE, MASSACHUSETTS 02139 83 04 29 018 ,' -.^. %. '" * ' 4. .-,. -i .- - k 7 . - . -. _. - .. .. .. - • . ... ..• . Unclassified "ECUtITY CLASSIFICATION OF THIS PAGE (When Data Entered) REPOT DCUMETATONPGE READ INSTRUCTIONS REPEN RTATIN OCU P GEBEFORE COMPLETING FORM 1. REPORT NUMBER 2. G 3. RECIPIENT'S CATALOG NUMBER LCS Progress Report 18 8'k, 4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED Laboratory for Computer Science DARPA/DOD, Progress Progress Report 18 Report 7/80 - 6/81 . July 1980 - June 1981 6. PERFORMING ORG. REPORT NUMBER LCS-PR 18 7. AUTHOR(s) 8. CONTRACT OR GRANT NUMBER(*) *Laboratory for Computer Science - Michael L. Dertouzos N00014-75-0661 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK - Laboratory for Computer Science AREA & WORK UNIT NUMBERS Massachusetts Institute of Technology .. 545 Tech. Sq. Cambridge, MA 02139 1i. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE -Defense Advanced Research Projects Agency April 1, 1983 * Information Processing Techniques Office 13. NUMBEROF PAGES * 1400 Wilson Blvd. Arlington, VA 22209 2R6 14. MONITORING AGENCY NAME & ADDRESS(f different from Controlling Office) IS. SECURITY CLASS. (of this report) Office of Naval Research " Department of the Navy Unclassified S.Information System Program 15a. DECLASSIFICATION/OOWNGRADING "" Arlington, VA 22217 " 16. DISTRIBUTION STATEMENT (of this Report) This - for pubhli ; .. - 17. DISTRIBUTION STATEMENT (of the abstract entered in Block 20, It different from Report) " 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reverse aide it necessary end identify by block number) Computation Structures Information Systems Office Automation Interactive Systems Personal Computers Computer Networks Local Networks Programming Language Computer Systems Message Systems rog ram Lang Dataflow Multiprocessing Real Time Computing Distributed Systems Network Semantics VLSsations Hardware Protocols Network Protocols Wor K 20. ABSTRACT (Continue on reverse aide if necesary ond Identify by block number) The report summarizes the research performed by the MIT Laboratory for Computer Science from July 1, 1980 through June 30, 1981. DO JAN73 1473 EDITION Of I NOV 65 IS OSSOLETE Unclassified S N 0102-LF-014-6601 SECURITY CLASSIFICATION OP TNIS PAGE f(When Dote IEnlaed) 77-73 MASSACHUSETTS LABORATORY FOR ISIUEO COMPUTER SCIENCE TECHNOLOGY PROGRESS REPORT 18 July 1980 - June 1981 Prepared for the Defense Advanced Research Projects Agency Effective date of contract: 1 January 1979 Contract expiration date: 31 December 1980 *Principal Investigator and Director: Michael L. Dertouzos (617) 253-2145 * ~Ifuintosselll h' supmortell by tile. 0, -f.....Aclvw dni llnro arch l,(ife( ts AqirrKy uto.. l Cijnlwt N'o NtXKI14 ?7, C 0661 * ViewS ard concluSions contained in this report are those of the authors and Should not be interpreted as representing the official opinions or Policy. either expiressed or implied of DARPA. the U.S. Government or any other parson or agency connected with them. This document is approved for Public release and sale, distribution is unlimited. 545 TECHNOLOGY SQUARE, CAMBRIDGE, MASSACHUSETTS 02139 TABLE OF CONTENTS INTRODUCTION 1 COMPUTER SYSTEMS AND COMMUNICATIONS 5 1. Introduction 7 2. Ringnet Hardware 7 3. MIT Internet 8 4. New Protocol Development 9 5. Protocol Performance 9 6. Multi-Protocol Computer Mail 10 7. Hand-Held Terminal 10 8. Other Activities 11 COMPUTER SYSTEMS STRUCTURE 15 1. Introduction 17 2. The SWALLOW Distributed Data Storage System 17 3. Debugging in a Distributed System 18 4. Systems Aspects of Encryption-Based Protection 18 " EDUCATIONAL COMPUTING 23 1. Introduction 25 2. Designing Systems for Non-Expert Users 26 . 3. A Boxer Overview 31 4. Sample Programs for Educational Use 40 5. Next Steps 47 FUNCTIONAL LANGUAGES AND ARCHITECTURE 51 " 1. Introduction 53 2. Language Related Work @ 53 3. A Dataf low Architecture and Prototype Implementation 54 '- INFORMATION MECHANICS 61 1. Conservative Logic and Reversible Computing 63 2. Semi-Intelligent Control r 64 4 MESSAGE PASSING SEMANTICS 67 . 1. Introduction 69 2. Workstation Network Semantics 69 " 3. Organizational Structure 71 4. The Nature of Office Work From an Al Perspective 75 5. Theoretical Foundations 79 6. An Evolutionary, Interactive Environment .- 83 7. Conclusions 84 'OFFICE AUTOMATION,' 91 1. Introduction 93 2. An Integrated Office Workstation 93 3. Functional Office Automation 118 4. Multi-Person Information Work 136 PROGRAMMING METHODOLOGY,' 159 1. Introduction 161 2. Atomicity 161 3. Guardians 169 4. Distributed Deadlock Detection 176 5. Orphans and Internal Consistency 179 PROGRAMMING TECHNOLOGY, 191 1. Introduction 193 2. Advanced Message Systems 193 3. Knowledge-Based Planning Aids 197 4. MDL 200 REAL TIME SYSTEMS) ,, 209 1. Introduction 211 2. Nu: The LCS Personal Computer 211 3. TRIX and UNIX Implementations on Nu 213 4. Object-Oriented Multiprocessing: The MuNet 213 5. VLSI Design tools 220 SYSTEMATIC PROGRAM DEVELOPMENT 229 1. Introduction 231 2. Formal Specification of Software 231 3. Rewrite Rule Theory 233 4. Synthesis of Implementations of Data Abstractions 234 5. Programming Languages 235 6. Interactions Outside of LCS 236 PUBLICATIONS 239 :4- *A ADMINISTRATION Academic Staff p M. Dertouzos Director M. Hammer Associate A.Meyer Director Associate Director Administrative Staff J. Badal Information M.Baker Specialist Administrative Assistant J. Hynes Administrative D.Wharen Officer Assistant Administrative Officer Support Staff G. Brown T.LoDuca S. Cavallaro D.Maupin R. Cinq-Mars E.Prof irio M. Cummings P.Vancini - I b Work reported herein was carried out within the Laboratory for Computer Science, an MIT interdepartmental laboratory. During 1980-81, the principle financal support of the Laboratory has come from the Defense Advanced Research Projects Agency (DARPA), under the Office of Naval Research Contract N0014-75-C-0661. DARPA has been instrumental in the last 18 years and is gratefully acknowledged here. Reproduction of this report, in whole or in part, is permitted for any purpose of the United States Government. Distribution of this report is unlimited. Assembly and production of this report was done by P. Vancini with assistance from A. Finn. - 'r-----° - -- INTRODUCTION The Laboratory for Computer Science is an interdepartmental laboratory whose principal goal is research in computer science and engineering. Founded in 1963 as Project MAC (for Multiple Access Computer and Machine Aided Cognition). the Laboratory developed the Compatible Time-Sharing System (CTSS), one of the first time-shared systems in the world, and Multics --an improved time-shared system that introduced several new concepts. These two major developments stimulated research activities in the application of on-line computing to such diverse disciplines as engineering, architecture, mathematics, biology, medicine, library science, and management. Since that time, the Laboratory's objectives expanded, leading to research across a broad front of activities that now span four principle areas. The first such area, entitled Knowledge Based Programs involves making programs more intelligent by capturing, representing, and using knowledge which is specific to the problem domain. Examples are the use of expert medical knowledge ,. for assistance in diagnosis carried out by the Clinical Decision Making Group; the use of mathematical knowledge by the Mathlab Group for an automated "mathematical assistant;" the use of knowledge in programs that comprehend typed natural language (English) queries; and the use of specific knowledge about budget for a budget planning system. Research in the second and largest area, entitled Machines, Languages and Systems, strives to effect sizable improvements in the ease of utilization and cost effectiveness of computing systems. For example, the Programming Methodology Group strives to achieve this broad goal through research in the semantics of geographically distributed systems. Toward the same goal, the Real Time Systems Group is exploring distributed operating systems and the architecture of single-user powerful computers that are interconnected by communication networks. Communication networks for such distributed environments are pursued by the * Computer Systems and Communications Group, while distributed file servers and . cryptographic protection techniques are pursued by the Computer Systems Structure Group. Other research in this area includes the architecture of very fast multiprocessor machines by the Computation Structures and Functional Languages and Architecture Groups, and the use of networks to link large numbers of " computers engaged in computationally intensive tasks. The Laboratory's third principal area of research, Theory, involves exploration and development of theoretical foundations in computer science. For example, the Theory