1. basic os function - resource management

   1. resources

      1. internal - cpu, memory, devices, files

      2. external - time, capital, bandwidth

   2. management - efficiently, conveniently, securely

2. os design issues - develop the abstractions

   1. performance - tradeoffs among various features

   2. protection and security - policy and mechanism

   3. correctness - trust, security, resilience

   4. maintainability - a complex piece of software

   5. commercial influence - the dead hand of the past

   6. standards and open systems - an alternative

3. os implementation issues

   1. os organization - performance vs. everything else

      1. monolithic - early, doesn't scale, os360, unix

      2. layered - also early, difficult to design, the THE

      3. object-oriented - abstraction-oriented, expensive, spring

      4. distributed - replicated or dispersed, sprite

      5. micro-kernel - a small monolith, expensive, mach and its follow-ons

      6. modular - a monolith with replaceable parts; linux, solaris

   2. processor modes

      1. supervisor vs. user operation - access to protected instructions

      2. moving between modes - traps, mode bits

   3. kernels - usually the protected part of the os

   4. service requests - system calls or message passing

This page last modified on 17 September 2001.