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CS350

CS350. Operating Systems. Administrivia. Assignments Homework on most chapters Approximately 8 lab assignments Exams Midterm Final (comprehensive) Quizzes Random, 10 minutes each Grades required to pass (after curving) >= 70 average on labs

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CS350

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  1. CS350 Operating Systems

  2. Administrivia • Assignments • Homework on most chapters • Approximately 8 lab assignments • Exams • Midterm • Final (comprehensive) • Quizzes • Random, 10 minutes each • Grades required to pass (after curving) • >= 70 average on labs • >= 70 average on (h/w + quizzes) together • >= 60 on midterm to pass

  3. Course Outline

  4. Introduction & Motivation • Wanted – a methodology to: • get more work done in a fixed time • allow multiple users on 1 computer • allow programs to interact with each other • maximize memory and CPU utilization • reduce the need for device handling • allow programs' parts to be shared • make the system more usable (friendlier?) • make system faster

  5. Why Study Operating Systems? • Understand support structure so we can: • Exploit system features • Learn to write more effective code • Learn to design an OS

  6. What IS an Operating System? • A "virtual machine" that provides: • An abstraction of some virtual computer • Common functionality for apps • Security across apps/devices • Some level of concurrency (maybe) • Portability across real machines • Simplified access to resources • Sharing of resources • Services for apps

  7. Perspectives • End user • Getting work done • Application programmer • More efficient use of system • Make work easier for user • O/S programmer • Exploit h/w • Enhance performance, usability

  8. Examples of System Software • Tools - a DBMS • API's - functions to create windows • Resident programs – resource mgmt

  9. Abstractions • User • Windows, folders • Application programmer • OS, language API's • Run-time libraries & DLL's • Shell • OS programmer • Hardware interfaces • Machine instructions • OS service interfaces

  10. Abstract View of System User Space Application Programming Interface O/S Space

  11. The API • Application Programming Interface • Exposes a portion of an environment • Provides services • I/O • Memory • Protection • Security

  12. Evolution of OS's • Uni-programming • DOS • Apparent multiprogramming • Windows Versions 2 to 3.1 • True multi-programming • UNIX/LINUX, OS/2, Windows95+ • Mainframe systems: • MVS, VMS, VM • Multithreading (mainstream systems) • OS/2 • System-V (AIX, Solaris, SCO Unixware) • Windows 95/98/NT/XP, 200x • Linux

  13. OS Strategies • Batch • All work pre-scheduled • Timesharing • Multi-user, Interactive • PC's and Workstations • Single-user, interactive • Embedded • Satellites, robots, etc • PDA's • Single-user, interactive, small • Network OS's • Multi-machine, multi-user

  14. Resource Management • Resources • Memory • CPU cycles • I/O • Includes networks, robot arms, motors • That is, any means of getting information (or signals) into or out of the computer

  15. Resource Sharing • Why do we need to share? • Greater throughput • Lowers cost of resources • Allows more resources to be available

  16. The Kernel • Implements O/S functions • Privileged, non-interruptible • Sometimes reduced to a "micro-kernel" • Absolutely minimal set of functions required to be in privileged mode • Micro-kernel does NOT include : • Device drivers • File services • Process server • Virtual memory mgmt

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