Course Overview

1
Course Overview

• Introduction
• Computer System Structures
• Operating System Structures
• Processes
• Process Synchronization
• Deadlocks
• CPU Scheduling

• Memory Management
• Virtual Memory
• File Management
• Security
• Networking
• Distributed Systems
• Case Studies
• Conclusions

2
Chapter Overview -- Introduction

• Motivation
• Course Objectives
• Course Prerequisites
• Relevance of OS mechanisms
• Scenarios
• Historical Perspective
• OS Examples
• Course Outlook
• Important Concepts and Terms
• Chapter Summary

3
Motivation

• OS is the glue between the computer systems
  hardware and the user interface and applications
• OS concepts help with the understanding of a
  computer systems operation
• the performance of a computer system depends as
  much on the efficient implementation of OS
  mechanisms as on the hardware computing power
• understanding of OS internals helps with the
  development of good and efficient software
• the selection of a computer system for a
  particular task or scenario must consider OS
  issues

4
Objectives

• appreciate the relevance of operating systems
• put operating systems in context with the overall
  computer system
• outline the relationships between various user
  activities, and how their needs are handled by
  the operating system
• provide an understanding for the historical
  development of operating systems
• identify important components of operating
  systems
• describe methods, algorithms and data structures
  used in operating systems
• discuss criteria, problems and trade-offs for
  design desicions

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Course Prerequisites

• basic knowledge of computer organization
• CPU, main memory, secondary storage, peripheral
  devices
• basic knowledge of computer usage
• operating system (Windows, MacOS, Unix)
• applications
• at least one programming language
• Pascal, C, C, Java, Fortran, assembly language
• data structures and algorithms
• array, list, tree, graph sorting, searching,
  etc.
• basic mathematics
• Boolean logic, binary and hexadecimal numbers

6
What this course is not

• It is not a course about one specific operating
  system
• it discusses general concepts
• sometimes reference is made to aspects of
  specific OSs as examples
• It is not an introduction on how to use certain
  operating systems
• it deals with design and implementation issues
  of OS concepts
• sometimes features of a specific OS may be used
  as examples to demonstrate the use of a method

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Where does the OS Fit?
Hardware
CPU Memory
I/O Devices
David Jones
8
Where does the OS Fit?
System Calls
Operating System
Hardware
CPU Memory
I/O Devices
David Jones
9
Where does the OS Fit?
Users and User Programs
System Calls
Operating System
Hardware
CPU Memory
I/O Devices
David Jones
10
Example Web Pages

• important aspects
• Web page design
• Web site design
• word processing
• graphics and animation
• sound and video
• data base

11
Web Page Design

• page layout
• format, components, arrangement on the page
• graphic elements
• logo, buttons, special effects, ...

12
Web Site Design

• site structure
• essential parts and their relationships
• overall layout
• format framework (font, headers, footers,
  background ...)
• graphic elements
• logo, buttons, ...
• implementation
• hardware, connection
• servers (Web, ftp, mail, newsgroups,...)
• additional applications (data base, audio, video,
  security, statistics)

13
Word Processing

• writing text
• formatting
• auxiliary tasks
• spell grammar checking
• constructing table of contents, index, etc.
• conversion to a Web-friendly format
• HTML, PDF, ASCII

14
Graphics and Animation

• drawing graphics
• application of effects
• developing animation
• objects involved
• trajectory
• changes in the objects over time
• conversion to a Web-friendly format
• animated GIFs, Shockwave, Java

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Images, Sound and Video

• capturing and recording of the material
• processing
• resolution, colors, effects
• editing
• selection of images, sounds, video frames
• sequences
• conversion to a Web-friendly format
• MPEG, Quicktime (?)

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Data Bases

• development of the data base
• elements to be stored
• entity-relationship diagram
• keys
• interface to the Web
• forms via HTML, Javascript, Java
• conversion to SQL, generation of the query
• search and presentation of the response

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Scenario 1 Webmaster Jill

• Web master Jill works on a page that provides
  access to a database containing information about
  the products her company offers
• she has a number of applications running
  simultaneously, and switches back and forth
• word processor
• Web page design tools
• graphics tool
• data base
• at the same time, she tests the page shes
  working on with a Web browser
• her computer is also used as Web server

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Scenario 2 Web Data Base

• information about products a company offers
• many queries resulting in short responses
• short CPU bursts, most of them with I/O
  activities to retrieve items from the data base
• http protocol is stateless
• no information is carried over between page
  requests of the same user
• it is difficult to predict or guess which item
  will be retreived next

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Scenario 3 Intranet Image Server

• central server holding photographs of an image
  agency (professional photographers)
• large file size
• high resolution
• millions of colors
• CPU mainly retrieves images from hard disk and
  transfers them onto the network
• activities during the transfer of an image are
  fairly predictable

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Active Tasks

• visible to the user
• word processor, Web page design tool, graphics
  tool, data base (client), browserbut also user
  interface
• not visible to the user
• Web server, data base server, auxiliary user
  programsbut also OS tasks administrating the
  available resources

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Primary User Needs

• immediate response to user actions
• typing, mouse movement, clicks
• up-to-date display of important activities
• arrival of e-mail, completion of a task
• quick switching between tasks
• good performance for relevant activities
• sharing of information across tasks
• convenient representation of information
• privacy

22
Secondary User Needs

• invisible tasks should have no effect on the
  users activities
• problems with one task leave other tasks
  unaffected
• information is stored automatically
• context-dependent user interface
• good resource utilization
• processing power, memory space
• ...

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OS Responsibilities

• handle simultaneous activities according to their
  importance
• allocate resources to the tasks as needed
• facilitate storage of and access to information,
  possibly by several tasks at the same time
• protect tasks from each other
• perform tasks invisible to the user in a
  non-obtrusive way

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OS Requirements

• quick response to user activities
• good performance
• subjective -- as perceived by the user
• objective -- according to some standardized
  measurements
• efficient resource utilization
• protection and security

25
OS Examples

• MVS, VMS
• Unix
• Windows 95, NT, Macintosh OS, OS/2, BeOS
• VxWorks

26
Historical Perspective

• computer systems
• theoretical concepts
• technological development
• computation, storage, input/output
• commercial use
• impact on users

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19th Century

• Analytical Engine Babbage Lovelace, 1834
• mechanical computing device, very limited
  programmability
• Boolean algebra Boole, 1854
• foundation for the operation of digital computers

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1930-1944

• electromechanical computers (relays, switches)
• Model 1 Bell Labs, 1930
• Zuse-1 Zuse, Austria/Germany, 1941
• MARK I Aiken, Harvard Univ., 1944
• electronic calculating device
• COLOSSUS Turing et al, Great Britain, 1938
• used to decipher German war communications

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1944-1954

• electrical computers (tubes, CRT displays)
• EDSAC Turing et al, 1949
• uses library of subroutines
• EDVAC von Neumann et al., 1951
• stored program computer, von Neumann architecture
• UNIVAC I Harvard, 1954
• IBM 650 1954
• first computer produced in series
• technology and concepts
• transistor Bell Labs, 1948
• assembler, compilers (Math_MATIC, Fortran) 1954
• microprogramming Wilkes, 1952

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1955-1964

• transistor-based computers (monitor, keyboard)
• TRIDAC
• DEC PDP-1 1959, PDP-8 1964
• IBM/360 1964
• technology and concepts
• Integrated Circuit (IC) Noyce Moore, 1959
• virtual memory U. of Manchester, England, 1958
• CTSS time sharing system Corbato, MIT, 1962
• ALGOL 58 Bauer et al., Munich, Germany, 1958
• PL/1, APL 1964

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1965-1974

• IC-based computers
• commercial success of mainframes
• IBM/360 family
• Control Data 6600 1965
• supercomputer
• DEC PDP-11 1972
• minicomputer

32
1965-1974 cont.

• technology and concepts
• Cache memory Wilkes, 1965
• microprocessor Intel 4004 Intel, 1971, Intel
  8008 Intel, 1972
• Winchester hard disk IBM, 1973
• ARPANet 1965 Ethernet Xeroc, 1973
• BASIC 1965, Simula Wirth, 1965, Pascal
  Wirth, 1970, C ATT, 1972, Smalltalk Xerox,
  1972
• OS/360 IBM, 1966, MULTICS MIT, 1966
• THE TH Eindhoven, Netherlands, 1968
• layer structure, concurrent processing
• Unix Thompson Ritchie, ATT, 1969

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1975-1984

• IC and microprocessor-based computers
• minicomputers take over tasks from mainframes
• Altair 8800 1975
• hobbyist computer, Intel 8080, 1K RAM
• personal computers
• Apple II, TRS 80, Commodore PET 1977
• IBM PC 1981, Compaq Portable 1982
• Apple Macintosh 1984
• DEC VAX 1978
• workstation
• graphical user interface, mouse, Ethernet,
  Smalltalk
• Xerox Star 1981
• SUN 1984

34
1975-1984 cont.

• technology and concepts
• Internet 1983
• CP/M operating system 1977
• VMS operating system DEC, 1978
• UNIX 3BSD 1979, SunOS 1984
• Ada 1979, Turbo Pascal 1982, Modula 2 1982
• Visicalc 1979
• PostScript 1984

35
1985-1994

• IC and microprocessor-based computers
• wide-spread use of personal computers
• work stations take over tasks from mainframes and
  minicomputers
• Cray-2 1985, Connection machine 1985
• PCs based on Intel 386 1987
• NeXT 1988

36
1985-1994 cont.

• technology and concepts
• Intel 80486 1989, Pentium 1993
• Alpha RISC chip 1992
• PowerPC 1993
• C 1985
• World Wide Web Berners-Lee, 1990
• MS Windows 1985, Windows 3.0 1990, Windows NT
  1993
• OS/2 1987
• Sun Solaris 1992
• Motif graphical user interface 1989
• local area networks 1987

37
1995- ???

• mainly microprocessor-based computers
• PDAs, e.g. Apple Newton 1995, PalmPilot
• Network Computer (NC) Oracle, 1996
• technology and concepts
• Intel Pentium Pro 1996
• PowerPC G3 1997
• Windows 95
• BeOS 1996
• Java Sun, 1995
• Y2K problem 2000
• will all computing come to a halt?

38
Important Concepts and Terms

• application programs
• CPU
• computer system
• graphical user interface
• hardware
• integrated circuit

• operating system
• processes, tasks
• resources, services
• software
• transistor
• user interface

39
Chapter Summary

• operating systems make the raw hardware usable
  for users and applications
• operating systems administer the resources of a
  computer system
• the most visible part of an operating system is
  the user interface
• determines the look and feel of a computer
  system
• has a very strong influence on the performance of
  a system as perceived by the user