1. Understanding Operating Systems Seventh Edition
Chapter 14 Windows Operating Systems

2. Learning Objectives
After completing this chapter, you should be able to describe:
Design goals for Windows operating systems designers
The role of the Memory Manager and Virtual Memory Manager in Windows
Its use of the Device, Processor, and Network Managers
System security challenges for Windows
Windows user interfaces
Understanding Operating Systems, 7e

3. Brief History
Windows products before 1995 release: Windows 95 operating system
Graphical user interfaces requiring the MS-DOS operating system
Disadvantages:
Multitasking not supported
Little built-in security
Lacked interprocess communication capability
Required customization to work with each system hardware component
Understanding Operating Systems, 7e

4. Understanding Operating Systems, 7e
(table 14.1)
Select Microsoft Windows operating systems. For details about these and other versions, refer to
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Understanding Operating Systems, 7e

5. Brief History (cont’d.)
Windows products since 1995
Abandoned MS-DOS reliance
More powerful networking products
Windows product version number
Windows XP: version 5.1
Windows 7: version 6.2
Windows 8: version 6.2
Display by pressing Windows logo key and the R key together
Type winver
Understanding Operating Systems, 7e

6. Design Goals Windows networking operating systems
Influenced by several operating system models
Employed already-existing frameworks
Introduced new features
Object model: manage and allocate resources
Symmetric multiprocessing (SMP): achieve maximum multiprocessor performance
Understanding Operating Systems, 7e

7. Design Goals (cont'd.) Needs Response Accommodate user needs
Optimize resources
Response
Five design goals
Extensibility
Portability
Reliability
Compatibility
Performance
Understanding Operating Systems, 7e

8. Extensibility Easily enhancing operating system
Ensuring code integrity: separate functions
Privileged executive process
Kernel mode
Processor’s mode of operation
All machine instructions allowed
System memory accessible
Nonprivileged processes protected subsystems
User mode
Certain instructions not allowed
System memory not accessible
Understanding Operating Systems, 7e

9. Extensibility (cont'd.)
Additional features
Modular structure
New components added to executive process
Objects
Abstract data types manipulated by special services
System resources managed uniformly
Remote procedure call
Application calls remote services
Regardless of location on network
Understanding Operating Systems, 7e

10. Portability Operates on different platforms
Different processors or configurations
Minimum amount of recoding
System guidelines to achieve goal
Written in a standardized, high-level language
Available in all machines
Accommodate ported hardware
Minimize direct code interaction with hardware
Reduce incompatibility errors
Isolate hardware-dependent code into modules
Easily modifiable when ported
Understanding Operating Systems, 7e

11. Portability (cont'd.) Windows features Modular code
Written in C (most of code)
Graphic component and some networking portions written in C++
Code communicating directly with hardware written in Assembly language
Hardware abstraction layer (HAL)
Dynamic-link library
Provides isolation from vendors’ hardware dependencies
Understanding Operating Systems, 7e

12. Reliability System robustness: error response predictability
Ability to protect itself and users
Accidental or deliberate user programs’ damage
Features strengthening system
Structured exception handling
Modular design
NTFS file system (NT File System)
Can recover from all error types
Advanced security architecture
Virtual memory strategy
Understanding Operating Systems, 7e

13. Compatibility
Execute programs written for other operating systems (or earlier system versions)
Use protected subsystems
Provide application execution different from primary programming interface
Provides source-level POSIX application compatibility
Recent Windows versions
Support existing file systems including MS-DOS FAT, CDFS, and NTFS
Built-in verification
Important hardware and software
Understanding Operating Systems, 7e

14. Performance Responds quickly to CPU-bound applications
Windows features
System calls, page faults, and other crucial processes: respond in timely manner
Incorporated local procedure call (LPC): guarantees fast communication among protected subsystems
Critical Windows networking software elements: built into operating system privileged portion
Understanding Operating Systems, 7e

15. Memory Management Every operating system Full physical memory
Has own physical memory view
Makes application programs access memory in specified ways
Full physical memory
Virtual Memory Manager pages some memory contents to disk
Challenge for all Windows operating systems
Run application programs (Windows or POSIX)
Without programs crashing into each other’s memory
Understanding Operating Systems, 7e

16. Memory Management (cont'd.)
Memory layout (recent Windows versions)
Operating system: high virtual memory
User code and data: low virtual memory
User process
Cannot read or write system memory directly
Memory paged to disk
User-accessible memory
System memory segment labeled paged pool
Memory never paged to disk
System memory segment labeled nonpaged pool
Understanding Operating Systems, 7e

17. Understanding Operating Systems, 7e
(figure 14.3)
Layout of Windows memory. This is a virtual memory system based on 32-bit addresses in a linear address space. The 64-bit versions use a similar model but on a much larger scale with 8TB for the user and 8TB for the kernel.
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Understanding Operating Systems, 7e

18. User-Mode Features VM Manager (virtual machine manager)
User-mode subsystems share memory efficiently
Provides native services: allows process to manage virtual memory
Allocate memory in two stages
Read and/or write protection for virtual memory
Lock virtual pages in physical memory
Retrieve information about virtual pages
Protect virtual pages
Rewrite virtual pages to disk
Understanding Operating Systems, 7e

19. Virtual Memory Implementation
VM manager reliance
Address space management
Paging techniques
Upper half of virtual address space
Accessible only to kernel-mode processes
Code in lower part (kernel code and data)
Never paged out of memory
Understanding Operating Systems, 7e

20. Virtual Memory Implementation (cont'd.)
Paging
VM manager part: transfers pages
Between memory page frames and disk storage
Complex combination
Software policies: when to bring a page into memory and where to put it
Hardware mechanisms: exact manner VM Manager translates virtual addresses into physical addresses
Pager not portable: modified for each new hardware platform
Windows: small code and well-isolated
Understanding Operating Systems, 7e

21. Virtual Memory Implementation (cont'd.)
Paging (cont’d.)
Processor chip translates program generated address into a physical address
Page with address not in memory: hardware generates a page fault and calls the pager
Processor uses translation look-aside buffer (TLB)
Speeds memory access
Understanding Operating Systems, 7e

22. Virtual Memory Implementation (cont'd.)
Paging policies
Dictate how and when paging is done
Composition
Fetch policy: determines when pager copies a page from disk to memory
Placement policy: determines where virtual page is loaded in memory
Replacement policy: determines which virtual page is removed from memory to make room for a new page
Understanding Operating Systems, 7e

23. Processor Management Process: Thread
Combination of executable program, private memory area, and operating system allocated resources as the program executes
Requires at least one execution thread
Thread
Process entity: roughly equated to a task
Understanding Operating Systems, 7e

24. Processor Management (cont’d.)
Windows
Preemptive-multitasking, multithreaded operating system
Process contains one thread composed of:
A unique identifier
Volatile set of registers: contents indicate processor’s state
Two stacks used during thread’s execution
Private storage area: used by subsystems and dynamic-link libraries
Understanding Operating Systems, 7e

25. Processor Management (cont'd.)
Threads
Thread components called thread’s context
Actual data forming context varies from one processor to another
Kernel
Schedules threads for execution on a processor
Thread actually executes code
Overhead incurred by thread is minimal
Unitasking
Process with single thread
Understanding Operating Systems, 7e

26. Processor Management (cont'd.)
(figure 14.4)
Unitasking in Windows. Here’s how a process with a single thread is scheduled for execution on a system with a single processor.
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Understanding Operating Systems, 7e

27. Processor Management (cont'd.)
Multithreading
Systems with multiple processors
Process has as many threads as CPUs available
All threads belonging to one process: share global variables, heap, and environment strings
Windows operating systems
Include some synchronization mechanisms
Give exclusive access to global variables as multithreaded processes execute
Understanding Operating Systems, 7e

28. Understanding Operating Systems, 7e
(figure 14.5)
Multitasking using multithreading. Here’s how a process with four threads can be scheduled for execution on a system with four processors.
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Understanding Operating Systems, 7e

29. Processor Management (cont'd.)
Multithreading example: modifying a database application
Entering records: one thread writes the last record to disk while another thread accepts new data
Database searching: several threads search an array simultaneously
Client/server applications: CPU-intensive for server
Client makes query requests; server’s processor manages the query
Windows handles requests allocating additional CPU resources
Understanding Operating Systems, 7e

30. Device Management Windows I/O system provides:
Multiple installable file systems (FAT, CDFS, and NTFS)
Services making device-driver development easy
Workable on multiprocessor systems
Drivers: added to or removed from system dynamically
System administrators
Fast I/O processing
Drivers written in high-level language
Mapped file I/O capabilities
Image activation, file caching, and application use
Understanding Operating Systems, 7e

31. Device Management (cont'd.)
I/O system
Packet driven
I/O request represented by I/O request packet (IRP)
IRP
Data structure controlling how I/O operation processed at each step
I/O manager:
Creates an IRP representing each I/O operation
Passes IRP to appropriate driver
Disposes packet when operation complete
Understanding Operating Systems, 7e

32. Device Management (cont'd.)
Driver IRP receipt
Performs specified operation
Passes it back to I/O manager or
Passes it through I/O manager to another driver for further processing
Understanding Operating Systems, 7e

33. Device Management (cont'd.)
I/O manager tasks
Supplies code, common to different drivers
Manages buffers for I/O requests
Provides time-out support for drivers
Records installable file systems loaded into operating system
Provides flexible I/O facilities
Subsystems (POSIX) implement their respective I/O application programming interfaces
Allows dynamic loading: device drivers and file systems based on users’ needs
Understanding Operating Systems, 7e

34. Device Management (cont'd.)
Windows I/O services
Device-independent model
Multilayered device driver concept
Device driver made up of standard set of routines
Initialization routine
Dispatch routine
Start I/O routine
Completion routine
Unload routine
Error logging routine
Understanding Operating Systems, 7e

35. Device Management (cont'd.)
I/O manager
Determines driver called to process request
Based on file object’s name
Driver object
Represents individual driver in system
Created by I/O manager when driver loaded into system
May have multiple device objects connected to it
Device object
Physical, logical, or virtual device on the system
Describes device characteristics
Understanding Operating Systems, 7e

36. Device Management (cont'd.)
(table 14.2)
Example showing how a device object is created from an instruction to read a file, illustrated in Figure 14.6.
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Understanding Operating Systems, 7e

37. Understanding Operating Systems, 7e
(figure14.6)
The driver object from Table 14.2 is connected to several device objects. The last device object points back to the driver object.
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Understanding Operating Systems, 7e

38. Device Management (cont'd.)
Device objects list
Represents physical, logical, virtual devices
Controlled by the driver
Advantages of using different objects
Portability
Frees I/O manager from knowing details about drivers
Follows pointer to locate driver
Easy loading of new drivers
Easy assigning drivers to control additional or different devices
System configuration changes
Understanding Operating Systems, 7e

39. Understanding Operating Systems, 7e
(figure14.7)
Details of the layering of a file system driver and a disk driver. The steps shown here take place when the I/O Manager needs to access a secondary storage device to satisfy the command shown in Step 1.
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Understanding Operating Systems, 7e

40. Device Management (cont'd.)
I/O manager knows nothing about file system
Overhead
I/O manager passes information requests back and forth
Uses single-layer device driver approach
Simple devices (serial and parallel printer ports)
Uses multilayered approach
More complicated devices (hard drives)
Asynchronous I/O operations
Nearly all low-level operations
Understanding Operating Systems, 7e

41. File Management Windows current versions Virtual file
Designed to be independent of file system on which they operate
Virtual file
Primary file handling concept (current Windows versions)
Programs perform I/O on virtual files
File handles manipulate them
Executive file object representing all I/O sources and destinations
Understanding Operating Systems, 7e

42. File Management (cont'd.)
Processes call native file object services to read from or write to file
I/O manager directs virtual file requests
Real files, file directories, physical devices, or other system-supported destinations
File objects
Hierarchical names
Protected by object-based security
Support synchronization
Handled by object services
Understanding Operating Systems, 7e

43. File Management (cont'd.)
Opening file
Process supplies file’s name and type of access required
File objects bridge gap
Between physical devices’ characteristics and directory structures, file system structures, and data formats
Understanding Operating Systems, 7e

44. File Management (cont'd.)
File object
Memory-based representation of shareable physical resources
Contains only data unique to an object handle
File
Contains data to be shared
New file object created with new set of handle-specific attributes
Each time process opens a handle
Understanding Operating Systems, 7e

45. Understanding Operating Systems, 7e
(figure14.8)
Illustrations of a file object, its attributes, and the services that operate on them. The attributes are explained in Table 14.3.
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Understanding Operating Systems, 7e

46. File Management (cont'd.)
(table 14.3)
Description of the attributes shown in Figure 14.8.
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Understanding Operating Systems, 7e

47. File Management (cont'd.)
Mapped file I/O: important I/O system feature
Achieved through cooperation between I/O system and VM Manager
Memory-mapped files exploit VM capabilities
Cache manager uses mapped I/O
Manages its memory-based cache
File management system
Supports long filenames
Include spaces and special characters
Automatically shortens filenames when required
Understanding Operating Systems, 7e

48. Network Management Networking
Integral part of Windows operating system executive
Provides services: user accounts and resource security
Implements communication between computers
Named pipes: provide high-level interface for passing data between two processes (regardless of locations)
Mailslots: provide one-to-many and many-to-one communication mechanisms
Understanding Operating Systems, 7e

49. Network Management (cont’d.)
Microsoft Networks (MS-NET)
Released in 1984
Model for NT Network Manager
Three components
Redirector
Server message block (SMB) protocol
Network server
MS-NET components
Extensively refurbished and incorporated into later Windows versions
Understanding Operating Systems, 7e

50. Network Management (cont'd.)
Redirector
Coded in C programming language
Implemented as loadable file system driver
Not dependent on system’s hardware architecture
Function
Direct I/O request from user or application to remote server with appropriate file or resource
Network can incorporate multiple redirectors
Understanding Operating Systems, 7e

51. Network Management (cont'd.)
SMB protocol
High-level specification
Formatting messages sent across network
OSI model correlation
Application layer (Layer 7); Presentation layer (Layer 6)
API called NetBIOS interface
Passes I/O requests structured in SMB format to remote computer
SMB protocols and NetBIOS API
Adopted in several networking products before appearing in Windows
Understanding Operating Systems, 7e

52. Network Management (cont'd.)
Windows Server operating systems
Written in C
Complete compatibility with existing MS-NET and LAN Manager SMB protocols
Implemented as loadable file system drivers
No dependency on hardware architecture
Where operating system running
Understanding Operating Systems, 7e

53. Directory Services Active Directory
Database storing many information types
General-purpose directory service for heterogeneous network
Built entirely around DNS and LDAP
Groups machines into domains
Each domain gets a DNS domain name (e.g., pitt.edu)
Each domain must have at least one domain controller
Domain can have more than one domain controller
Active Directory clients use standard DNS and LDAP protocols: locate objects on the network
Understanding Operating Systems, 7e

54. Understanding Operating Systems, 7e
(figure 14.9)
Active Directory clients use standard DNS and LDAP protocols to locate objects on the network.
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Understanding Operating Systems, 7e

55. Security Management Windows network operating systems
Provide object-based security model
Security object
Represents any resource in system (file, device, process, program, or user)
Allows administrators to give precise security access
Monitor and record how objects used
Windows biggest concern
Aggressive patch management needed
Combat many viruses and worms
Understanding Operating Systems, 7e

56. Security Concerns U.S. Department of Defense
Identified and categorized seven levels of security features
Class C2 security level compliance
Features in Windows
A secure logon facility
Discretionary access control
Auditing ability
Memory protection
Understanding Operating Systems, 7e

57. Security Concerns (cont'd.)
Multilayered security system
First security layer: password management
Second security layer: file access security
Distinguishes between owners and groups
Users decide operation types person is allowed to perform on a file
Gives user auditing capabilities: automatically tracks who uses files and how files used
Understanding Operating Systems, 7e

58. Security Terminology Built-in security
Necessary element for managers of Web servers and networks
Requires authentication mechanism allowing client to prove identity to server
Client supplies authorization information
Server uses information: determines specific access rights given to client
Provides data integrity using various methods
Windows operating systems feature Kerberos security
Understanding Operating Systems, 7e

59. Security Terminology (cont'd.)
Kerberos security
Authentication (mutual), data integrity, and data privacy
Each domain has own Kerberos server
Microsoft implemented standard Kerberos protocol
Microsoft separates distributed security services users from their providers
Supports many options without unusable complexity
Understanding Operating Systems, 7e

60. Security Terminology (cont'd.)
(figure 14.10)
Requests from an application flow through these security stops on the way to and from the network.
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Understanding Operating Systems, 7e

61. User Interface Windows 8 Windows Task Manager
Offers same default screen
All devices running the operating system
Laptop or desktop users
Can switch between tile-populated Start screen and Desktop screen
Windows Task Manager
Open: press and hold Ctrl, Alt, and Delete keys together
Understanding Operating Systems, 7e

62. Understanding Operating Systems, 7e
(figure 14.13)
Using the Task Manager, users can view the system status, assign priorities, and more.
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Understanding Operating Systems, 7e

63. Understanding Operating Systems, 7e
(figure 14.14)
The resource monitor offers running statistics for this session.
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Understanding Operating Systems, 7e

64. User Interface (cont’d.)
Command-line interface
Available from most Windows desktops
Use Help feature: learn a command’s syntax
Understanding Operating Systems, 7e

65. Understanding Operating Systems, 7e
(table 14.4)
Selected commands that can be used in the Command Prompt Window. For a complete listing, see your technical documentation or © Cengage Learning 2014
Understanding Operating Systems, 7e

66. User Interface (cont'd.)
Helpful Windows features
Built-in input methods and fonts for many languages
Accommodates users working in non-English languages
Enhanced accessibility options
On-screen keyboard
Other tools: magnifier, a narrator, speech recognition, etc.
Understanding Operating Systems, 7e

67. Conclusion Windows operating systems Windows 8 Windows recognized as:
Started as a microcomputer operating system
Now includes complex multiplatform software
Run computing systems of all sizes
Windows 8
Singular interface
Both touch screens and traditional computers
Windows recognized as:
Powerful operating system
Significant market force
Understanding Operating Systems, 7e