1. Lecture 8: 9/19/2002CS149D Fall 20021 CS149D Elements of Computer Science Ayman Abdel-Hamid Department of Computer Science Old Dominion University Lecture 8: 9/19/2002

2. CS149D Fall 20022 Outline Wrap up Chapter 2 Problems 2.10, 2.20 How CPU and memory communicates with other devices Chapter 3Operating Systems and Networks Evolution of Operating Systems Operating System Architecture Should cover sections 3.1 and 3.2

3. Lecture 8: 9/19/2002CS149D Fall 20023 Communication with Other devices Fig. 2.8 on page 100 Copyright © 2003 Pearson Education, Inc.

4. Lecture 8: 9/19/2002CS149D Fall 20024 Evolution of Operating Systems An operating System (OS) controls and coordinates usage of a machine’s resources (CPU, memory, disks, …) Single-processor machines in 1940s and 1950s Significant preparation of equipment to run a program Execution of a program  job Separation of users and equipments (introduction of computer operator concept) Submit program to operator to run, along with any required data and special directions Operator loads program materials into machine’s mass storage Batch processing

5. Lecture 8: 9/19/2002CS149D Fall 20025 Batch Processing Copyright © 2003 Pearson Education, Inc. No interaction with the program once submitted

6. Lecture 8: 9/19/2002CS149D Fall 20026 Interactive Processing What happens when you have multiple users? Time-sharing solution (time slices) (In single-user systems usually called multitasking) Copyright © 2003 Pearson Education, Inc.

7. Lecture 8: 9/19/2002CS149D Fall 20027 Software Classification Copyright © 2003 Pearson Education, Inc. Application: spreadsheets, games, program development software Utility: utility to format a disk, copy a file, utility to handle network communication

8. Lecture 8: 9/19/2002CS149D Fall 20028 Operating System Components Copyright © 2003 Pearson Education, Inc. Shell: interface between users and operating system. Modern computers have a GUI shell (Graphical User Interface) Window manager: component within the GUI shell Kernel: internal part of an OS

9. Lecture 8: 9/19/2002CS149D Fall 20029 OS Kernel Software Components File Manager Coordinate use of machine’s mass storage Device drivers Control operation of machine’s peripheral devices (printer, disk drive, monitor, …) Memory Manager Coordinate machine’s use of main memory Scheduler Which activity is executed next Dispatcher Controls allocation of time slices to activities

10. Lecture 8: 9/19/2002CS149D Fall 200210 Boot Strapping an OS Copyright © 2003 Pearson Education, Inc.