The architecture of computer hardware and systems software an information technology approach ch13

Chapter 13 Operating Systems: An Overview The Architecture of Computer Hardware and Systems Software: An Information Technology Approach 3rd Edition, Irv Englander John Wiley and Sons 2003 Bare Bones Computer System  Does not load instructions into main memory  No user interface except for I/O routines provided with executing program  Is idle when waiting for user input  No facility to store, retrieve, or manipulate files  No ability to control peripheral devices  Can run only one program at a time Chapter 13 13-2 Integrated Computer Environment Chapter 13 13-3 Operating System – Basic Services  Programs that accept commands and requests from a user and a user’s program  Manages, loads, and executes programs  Manages hardware resources of the computer  Act as an interface between the user and the system Chapter 13 13-4 Operating System – Additional Services  Provides interfaces for the user and the user’s programs  File support services  I/O support services  Means of starting the computer  Bootstrapping or booting the computer  Initial Program Load (IPL)  Handles all interrupt processing  Network services  Provides tools and services for concurrent processing Chapter 13 13-5 Additional Services Required by Concurrent Processing  Allocates resources such as memory, CPU time, and I/O devices to programs  Protects users and programs from each other and provides for inter-program communication  Provides feedback to the system administrators to permit performance optimization of the computer system Chapter 13 13-6 OS Parts  Memory Resident  Always loaded in memory  Commonly called the kernel  Contains essential services required by other parts of the operating system and applications  Typically responsible for managing memory management, processes and tasks, and secondary storage  Memory Non-resident  Applications  Infrequently used programs, software tools, and commands  Bootstrap program  Diskless workstations or thin clients  Programs, including the OS, are located on another computer on the network Chapter 13 13-7 Simplified Diagram of Operating System Services Chapter 13 13-8 OS Degree of Activity  Interactive  Also known as conversational systems  Batch processing  User submits programs or jobs for processing  Little to no user interaction  Event driven  Interrupts or service requests Chapter 13 13-9 Hardware and the OS  A hardware platform may support a variety of operating systems  An operating system may work on a variety of platforms  A standard operating system that works on different hardware  Provides program and file portability  Enables user efficiency through recognizable interface  Is implemented through a systems programming language like C or C++ as opposed to assembly language Chapter 13 13-10 User Interface and Command Execution Services  Types of user interfaces  CLI - Command Line Interface  GUI - Graphical User Interface  Menu environment  Shell  User interface and command processor that interacts with the kernel  UNIX: C, Bourne and Korn shells  Command Languages  IBM Mainframes – JCL  MS Windows – BAT files, Windows Scripting Host  UNIX – shell scripts Chapter 13 13-20 File Management  File - logical unit of storage  Basic file management system provides  Directory structures for each I/O device  Tools to copy and move files  Information about each file in the system and the tools to access that information  Security mechanisms to protects files and control access  Additional file management features     Backup, emergency retrieval and recovery File compression Transparent network file access auditing Chapter 13 13-21 I/O Services and Process Control Management  I/O services  Startup configuration  Device drives that implement interrupts and provide other techniques for handling I/O  Plug and play: hot swapping, hot plugging  Process control management  A process is an executing program  A thread is an individually executable part of a process  Interprocess messaging services  Example: a pipe in UNIX or DOS that is a temporary software connection between two programs or commands Chapter 13 13-22 Memory Management  Keeps track of memory     Identifies programs loaded into memory Amount of space each program uses Available remaining space Prevents programs from reading and writing memory outside of their allocated space  Maintains queues of waiting programs  Allocates memory to programs that are next to be loaded  Deallocates a program’s memory space upon program completion Chapter 13 13-23 Scheduling  High-level scheduling  Placed in queue based on level of priority and eventually executed  Dispatching  Actual selection of processes that will be executed at any given time  Preemptive – uses clock interrupts  Non-preemptive – program voluntarily gives up control  Context switching  Transfer control to the process that is being dispatched  Nonpreemptive: program voluntarily gives up control  Preemptive: uses clock interrupt for multitasking  Processing requirements  CPU vs I/O bound Chapter 13 13-24 Secondary Storage and Security  Secondary storage management  Optimizes completion of I/O tasks for efficient disk usage  Combination of hardware and software  Security and protection services     Protect OS from users Protect users from other users Prevent unauthorized entry to system Prevent unauthorized system use by authorized users Chapter 13 13-25 Network and Communication Services  TCP-IP protocol suite  Locate and connect to other computers  Access files, I/O devices, and programs from remote systems  Support distributed processing  Network Applications  Email, remote login, Web services, streaming multimedia, voice over IP telephony, VPN  Interface between communication software and OS I/O control system that provides network access Chapter 13 13-26 System Administration Support  System configuration and setting group configuration policies  Adding and deleting users  Modifying user privileges  System security  Files systems management Chapter 13  Network administration  Backups  Software installations and upgrades  OS installations (system generation), patches, and upgrades  System tuning and optimization 13-27 Monolithic Kernel  Drawback: stability and integrity  Examples:  UNIX  Windows NT Chapter 13 13-28 Hierarchical  Requests pass through intermediate layers  Examples  Multics  Data General Chapter 13 13-29 Microkernel  Minimum essential functionality  Client-server system on same system  Clients request services from microkernel which passes message onto appropriate server Chapter 13 13-30 Mach OS Kernel  Microkernel implementation  Includes      Message passing Interrupt processing Virtual memory management Scheduling Basic set of I/O drivers  Macintosh OS X, IBM AIX on RS/6000 Chapter 13 13-31 Types of Operating Systems     Single user, single tasking Single user, multitasking Multi-user, multitasking Distributed systems  Processing power distributed among computers in a cluster or network  Network servers  Real-time systems  Embedded systems Chapter 13 13-32 Bootstrapping  Execution begins with bootstrap loader (mini-loader, IPL) stored in ROM  Looks for OS program in a fixed location  Loads OS into RAM  Transfers control to starting location of OS  Loader program in OS used to load and execute user programs Chapter 13 13-33 Bootstrapping  Cold vs warm boot (does not retest the system) Chapter 13 13-34 ... accept commands and requests from a user and a user’s program  Manages, loads, and executes programs  Manages hardware resources of the computer  Act as an interface between the user and the system... for the user and the user’s programs  File support services  I/O support services  Means of starting the computer  Bootstrapping or booting the computer  Initial Program Load (IPL)  Handles... called the kernel  Contains essential services required by other parts of the operating system and applications  Typically responsible for managing memory management, processes and tasks, and