Contents

• Contents
• ASSORTED INITIAL CONSIDERATIONS
  • INTRODUCTION
  • THE PROJECT
  • THE HARDWARE
  • FUNDAMENTAL IDEAS
    • 1) Specification as an Abstract Machine
    • 2) Capability-Based Protection System
    • 3) Processes
    • 4) Mapped Address Space
    • 5) Layered Implementation
    • 6) Distributed System Code
    • 7) Uninterpreted I-O Devices
    • Origins
  • REQUIREMENTS IMPOSED BY SOME KINDS OF USER LEVEL PROGRAMS
    • 1) Scope system simulator
    • 2) Text file editor
    • 3) Debugger
    • 4) Device drivers
    • 5) Typical user Fortran programs
• THE SYSTEM
  • BASIC ARCHITECTURAL CONSIDERATIONS
    • Swapping
    • Input-output strategy
    • Layers
  • ECS SYSTEM ARCHITECTURE
    • Brief sketch
    • The abstract machine
    • ECS files
    • Event channels
    • Processes
    • Maps
    • Subprocess call stack
    • Subprocess tree
    • Actions involving processes
    • C-lists (and capabilities)
    • Capability-creating-authorization
    • Operations
    • F-returns (failure-return)
    • Multi-level operations
    • Actions on operations
    • Class-codes
    • Allocation blocks
  • STATE REPRESENTATION IN THE ECS SYSTEM
    • Storage allocator
    • Unique name
    • Master object table (MOT)
    • Capability list
    • Files
    • Event channels
    • Other types of objects
  • ECS SYSTEM I-O FACILITIES
    • Teletype I-O interface
    • Magnetic tape I-O interface
    • Disk I-O package
  • DISK/DIRECTORY SYSTEM
    • Disk files
    • Access keys and locks
    • Directories
    • Disk space control
    • Name-tags
    • Subprocess descriptors
    • Scan lists
  • IMPLEMENTATION OF DISK DIRECTORY SYSTEM
    • Disk-directory system code within a user process
    • Special system processes (non user processes)
    • Disk file capabilities
    • Directory system directories
    • Dynamic name-tags
  • A CONSISTENCY PROBLEM FOR DISK FILES
    • The problem
    • The problem will also occur in other systems
    • Consequences of the problem
    • A solution
    • Discussion
  • COMMAND PROCESSOR
    • Octal debugger
    • Subprocess construction
    • TTY line collector
    • Naming
    • Passwords and accounting
  • A SHORT TOUR OF A USER PROCESS
    • Root
    • Builder
    • Fake bead ghost
    • Disk F-return read write
    • Disk
    • Directory
    • Bead Services
    • Bead ghost
    • TTY line collector
    • CMMD
    • User
• ASSORTED REACTIONS
  • DISCUSSION
    • Disappointments
    • The fundamental ideas
    • Support for special user level programs
  • A SUCCESS
    • Unified conceptual framework
    • Easy to understand protection
    • Modularity with clean interfaces
    • It resulted in an almost error free ECS system
  • SOME DISAGREEABLE FACTS
    • Large
    • Slow
    • Difficult to use
  • SPEED UPS
    • Direct ECS access
    • Fast actions
    • Effect on the disk system
  • HARDWARE HELP
    • Sketch of entry to a system action
    • Many base bound pairs
    • Hardware capabilities
    • Capability memory reference instructions
    • Data memory reference instructions
    • Data manipulation instructions
    • Capability manipulation instructions
    • Reduce access bits
    • Read or write the datum part of a datum capability
    • Lock or unlock a capability
    • Create a new lock and key
    • Example
  • A REPLACEMENT FOR OUR MAP FACILITY
    • Disaster
    • An alternative
  • DISTRIBUTED SYSTEM CODE
  • SUMMARY AND PARTING WORDS
    • Summary
    • Parting words
  • PROJECT HISTORY
  • PROJECT MEMBERS