Overview

• Introduction
  • The Big Picture
    • Foundations
      • Religion
      • Physics
      • Chemistry
    • Hardware - provides basic computing resources (CPU, memory, I/O devices).
      • Electronics
      • Computer Systems
    • Computer Science
      • Operating Systems
      • Programming
      • Analysis
      • Application Building Tools
    • The World
      • Information Technology
      • Applications programs - define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs).
      • Users (people, machines, other computers).
  • The Software Picture
    • Problems + Analysis and Design = Algorithms
    • Algorithms + Programming = Programs
    • Programs + Compilers = Relocatable executables
    • Relocatable executables + Linker-loader = Executable
    • Executable + Operating Systems = Execution on hardware
    • Execution on hardware + Time and Space and Randomness = Solutions
  • What is an OS? (SGG Ch.1.1)
    • Operating system - controls and coordinates the use of the hardware among the various application programs for the various users.
    • A program that acts as an intermediary between user programs and the computer hardware.
    • Operating system goals:
      • Execute user programs
      • Make the computer hardware convenient to use.
      • Use the computer hardware in an efficient manner.
      • Maintain protection and security

• Software Execution
  • Executables
    • Source code
    • Compilation
    • Linking
    • Machine code
      • Text segment - 0 base address
      • Data segment
      • Stack-heap segment(s)
  • von Neumann architecture (BH pp.11-13,53)
    • CPU
      • ALU
      • Registers: MAR, MBR, PC, IR, SR, ACU, Base, Limit, R0 ...
      • Cache
      • CPU bus
    • Interrupt vector (BH pp.143-152)
    • MMU and RAM
    • IO devices
    • System bus
    • DMA channel
  • Computer system operation (SGG Ch.2.1)
    • Memory read and write, using the MAR and MBR and MMU
    • The interrupt?-fetch-decode-execute-increment cycle (BH pp.13-14)
    • Interrupt handling
      • Save state
      • Branch to OS
      • Restore state
  • The startup sequence (BH pp.131-132)
    • Initialize registers
    • Put ROM start address (or indirect address) in PC
    • Start fetch-decode-execute cycle
    • Load boot block from boot disk
    • Execute boot block
    • Load OS from disk to RAM
    • Start OS processes
    • Wait for interrupt
      • Tight loop
      • "Halt" instruction (cooler :-)
  • Interrupts
    • The only way for the OS to gain control
    • Sources of interrupts
      • Devices, particularly IO
      • Software (traps)
      • Hardware (including errors)
      • Clock
    • Styles of handling
      • Interrupt line, universal handler
      • Interrupt line, handler chain
      • CPU vector
    • Saving the state - where does it go?
      • Process control blocks
      • Register banks
      • Interrupt stack
    • Interrupting an interrupt
      • Interrupt stack (for nested interrupts)
      • Disabling interrupts
      • Queueing interrupts
      • Interrupt levels

• History and Hardware (Slides)
  • The story that motivates multi-tasking (SGG Ch.1.2)
    • Early systems (BH pp.5-7)
    • Batch systems
    • Offline operation
    • Spooling
    • IO system hardware
    • IO interrupts (SGG Ch.2.2.1)
    • Multiprogrammed batched systems
    • Timesharing systems
  • Hardware protection (SGG Ch.2.5)
    • Dual mode operation (SGG Ch.2.5.1, BH pp.71-72)
      • Bit in CPU
    • CPU protection (SGG Ch.2.5.4)
    • Memory protection (SGG Ch.2.5.3)
    • IO protection (SGG Ch.2.5.2)
  • Other types of systems (SGG Ch1.3-8)
    • Personal computer systems
    • Multiprocessor systems
    • Distributed systems
    • Real time systems
    • Handheld systems
    • Feature migration (SGG Ch.1.9)

• OS structures (Slides)
  • System components (SGG Ch.3.1)
    • Process management (SGG CH.3.1.1)
    • Memory management (SGG Ch.3.1.2)
    • File management (SGG Ch.3.1.3)
    • IO system management (SGG Ch.3.1.4)
    • Secondary storage management (SGG Ch.3.1.5)
    • Network management (SGG Ch.3.1.6)
    • Protection system (SGG Ch.3.1.7)
  • System services
    • For the user (SGG Ch.3.2)
    • For the programmer (SGG Ch.3.3)
    • For the system (SGG Ch.3.2)
    • System programs
      • Types of programs (SGG Ch.3.4)
      • Command interpreter (SGG Ch.3.1.8, Ch.3.4)
  • System structure
    • Simple approach (SGG CH.3.5.1)
    • Layered approach (SGG Ch.3.5.2)
    • Microkernels (SGG Ch.3.5.3)
    • Virtual machines (SGG Ch.3.6)
    • Design and implementation (SGG Ch.3.7-8)
  • UNIX
    • UNIX structure (SGG Ap.A.2)
    • UNIX system calls (SGG Ap.A.3)

Exam Style Questions

• Draw a diagram showing how the operating system relates to users, application programs, and the computer hardware.
• Why are interupts and interupt handling crucial to time-sharing operating systems?
• What is SPOOLING?
• Explain the difference between synchronous and asynchronous IO.
• What OS features are required for multiprogramming?
• What extra acpability does a time-sharing OS offer over a multi-programming OS?
• What is the difference between kernel and user mode of a CPU?
• Explain how dual mode operation is used in {memory,IO,CPU} protection.
• How does a modern computer prevent a process from using the CPU for ever?
• What OS feature is less crucial in PC systems?
• What extra capability does an OS require to be used on a SMP machine?
• Explain the differences between OSs for hard real time and soft real time computing.
• Name are the five core software modules of a modern OS?
• What activities is the OS involved with in {process,memory, file, IO system, disk} management?
• Explain three ways that data may be passed from a user process to the OS.
• Describe the layered approach to OS structure.
• What is the principle idea of a micro-kernel OS?
• Draw a diagram showing the architecture of a virtual machine OS model.
• How can OS implementation affect the potential for porting to another machine? How can the porting effort be minimized?
• What happens in OS sysgen?