1. Understanding Operating Systems Fifth Edition
Chapter 15 Windows Operating Systems

2. Learning Objectives The role of MS-DOS in early Windows releases
The design goals for Windows operating systems
The role of the Memory Manager and Virtual Memory Manager
The use of the Device, Processor, and Network Managers in recent versions of Windows
The challenges for Windows system security
How the current Windows user interface functions
Understanding Operating Systems, Fifth Edition

3. Windows Development First Windows product communication method
Graphical user interface (GUI)
Primary user communication method
Needed underlying operating system to translate users’ requests into system commands
Windows 1.0 (1985)
First Windows application
Ran on PC-compatible microcomputers
Not a true operating system
Ran on top of MS-DOS
Interface between MS-DOS and user
Understanding Operating Systems, Fifth Edition

4. Early Windows Products
Advancements in Windows
Increasingly sophisticated GUI design
Increasingly powerful desktop computers
Windows 3.1
Standardized look and feel
Similar to Apple’s Macintosh computer
Entry level product
Single-user installations or small-business environments
Understanding Operating Systems, Fifth Edition

5. Early Windows Products (continued)
Windows for Workgroups
Accommodate network users’ needs (small business)
Programs and features for small LANs
Share directories, disks, printers
Personal intercommunication: , chat programs
Understanding Operating Systems, Fifth Edition

6. Operating Systems for Home and Professional Users
Disadvantages running Windows on MS-DOS
Little built-in security
No multitasking
No interprocess communication capability
Difficulty moving MS-DOS to other platforms
MS-DOS worked closely with hardware
Microsoft response
Developed and released succession of Windows
Not mere GUIs; had home and office user appeal
Development of powerful networking products
Windows NT (Newer Technology)
Understanding Operating Systems, Fifth Edition

7. Operating Systems for Home and Professional Users (continued)
Understanding Operating Systems, Fifth Edition

8. Operating Systems for Networks
Windows NT Development (1993)
No reliance on MS-DOS support
Primary market requirements
Portability
Multiprocessing capabilities
Distributed computing support
Government procurement compliance requirements
Government security certification
Understanding Operating Systems, Fifth Edition

9. Operating Systems for Networks (continued)
Understanding Operating Systems, Fifth Edition

10. Operating Systems for Networks (continued)
Windows NT versions
Windows NT Workstation
Individuals
Desktop operating system
Windows NT Server
Small to medium-sized offices
Web servers and off-site locations
Windows NT Server Enterprise Edition
Larger and more complex networks
Understanding Operating Systems, Fifth Edition

11. Operating Systems for Networks (continued)
Windows NT name changed (1999)
Windows 2000 four packages
Windows 2000 Professional
Windows 2000 Server
Windows 2000 Advanced Server
Windows 2000 Datacenter Server
Large data warehouses
Data-intensive business applications
Supported up to 64 GB physical memory
Windows Server 2003
Same four packages plus Web edition
Understanding Operating Systems, Fifth Edition

12. Operating Systems for Networks (continued)
Server and Advanced Server editions
Easy
Form collaborative work groups across departments
Add new workstations and components
Improvements
Network systems
Adding new applications
Maintaining system as a whole
Web server software tools and support
, conferencing, and collaboration
Understanding Operating Systems, Fifth Edition

13. Design Goals Fulfilling marketing requirements
Incorporate security features
Facilitate decision making (coding process)
Windows networking operating systems
Influenced by several operating system models
Use already-existing frameworks
Introduced new features
Object model
Manage and allocate resources
Symmetric multiprocessing (SMP)
Maximum multiprocessor performance
Understanding Operating Systems, Fifth Edition

14. Design Goals (continued)
Needs
Accommodate user needs
Optimize resources
Response
Five design goals
Extensibility
Portability
Reliability
Compatibility
Performance
Understanding Operating Systems, Fifth Edition

15. 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, Fifth Edition

16. Extensibility (continued)
Four more features
Modular structure
New components added to executive process
Objects
Abstract data types manipulated by special services
System resources managed uniformly
Drivers
New file systems, devices, and networks added to system at any time
Remote procedure call
Application calls remote services
Regardless of location on network
Understanding Operating Systems, Fifth Edition

17. Portability Operate on different machines
Different processors or configurations
Minimum amount of recoding
System guidelines to achieve goal
Written in a standardized, high-level language
Available in all machines
Accommodated ported hardware
Minimized direct code interaction with hardware
Reduced incompatibility errors
Hardware-dependent code isolated into modules
Easily modifiable when ported
Understanding Operating Systems, Fifth Edition

18. Portability (continued)
Windows NT and successors’ features
Modular code
Written in C (most of code)
Hardware abstraction layer (HAL)
Dynamic-link library
Provides isolation from vendors’ hardware dependencies
Understanding Operating Systems, Fifth Edition

19. Reliability Robustness of system 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, Fifth Edition

20. 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
FAT, CDFS, NTFS
Built-in verification
Important hardware and software
Understanding Operating Systems, Fifth Edition

21. Performance Achieve good performance levels Windows features
Testing and optimization system calls, page faults, crucial processes
Incorporate local procedure call (LPC): guarantee fast communication among protected subsystems
Maximize speed of frequently used system services
Critical Windows networking software elements built into operating system privileged portion
Understanding Operating Systems, Fifth Edition

22. 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, POSIX)
Without programs crashing into each other’s memory
Understanding Operating Systems, Fifth Edition

23. Memory Management (continued)
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, Fifth Edition

24. Memory Management (continued)
Understanding Operating Systems, Fifth Edition

25. User-Mode Features VM Manager (virtual machine manager)
User-mode subsystems share memory efficiently
Provides process services 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, Fifth Edition

26. 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, Fifth Edition

27. Virtual Memory Implementation (continued)
Paging (VM manager is pager)
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
Windows: small code and well isolated
Understanding Operating Systems, Fifth Edition

28. Virtual Memory Implementation (continued)
Paging policies
Dictate how and when paging 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, Fifth Edition

29. Processor Management Windows Windows NT process Default
Preemptive-multitasking, multithreaded operating system
Windows NT process
Requires at least one thread
Default
Process contains one thread
Understanding Operating Systems, Fifth Edition

30. Processor Management (continued)
Thread composition
A unique identifier
Contents of volatile set of registers indicating processor’s state
Two stacks used during thread’s execution
Private storage area: used by subsystems and dynamic-link libraries
Understanding Operating Systems, Fifth Edition

31. Processor Management (continued)
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, Fifth Edition

32. Processor Management (continued)
Understanding Operating Systems, Fifth Edition

33. Processor Management (continued)
Multithreading using multitasking
Systems with multiple processors
Process has as many threads as CPUs available
All threads belonging to one process: share global variables, heap, environment strings
Versions of Windows since NT
Include some synchronization mechanisms
Avoid problems with multiple threads
Understanding Operating Systems, Fifth Edition

34. Processor Management (continued)
Understanding Operating Systems, Fifth Edition

35. Device Management
Windows NT I/O system and networking descendents provide:
Multiple installable file systems (FAT, CDFS, NTFS)
Services making device-driver development easy
Workable on multiprocessor systems
Adding drivers to the system (system administrators)
Remove them dynamically
Fast I/O processing
Drivers written in high-level language
Mapped file I/O capabilities
Image activation, file caching, application use
Understanding Operating Systems, Fifth Edition

36. Device Management (continued)
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 IRP creation
Creates an IRP representing each I/O operation
Passes IRP to appropriate driver
Disposes of packet when operation complete
Understanding Operating Systems, Fifth Edition

37. Device Management (continued)
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, Fifth Edition

38. Device Management (continued)
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 of device drivers and file systems
Based on users’ needs
Understanding Operating Systems, Fifth Edition

39. Device Management (continued)
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, Fifth Edition

40. Device Management (continued)
I/O manager
Determine driver called to process request
Using file object’s name
Driver object
Represents individual driver in system
I/O manager creates
Created 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, Fifth Edition

41. Device Management (continued)
Understanding Operating Systems, Fifth Edition

42. Device Management (continued)
Understanding Operating Systems, Fifth Edition

43. Device Management (continued)
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
If system configuration changes
Understanding Operating Systems, Fifth Edition

44. Device Management (continued)
Understanding Operating Systems, Fifth Edition

45. Device Management (continued)
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)
I/O operations asynchronous
Almost all low-level operations
Understanding Operating Systems, Fifth Edition

46. File Management Windows current versions
Designed to be independent of file system on which they operate
Support multiple file systems for hard disks including:
MS-DOS’s FAT file system
32-bit FAT file system
NTFS
Understanding Operating Systems, Fifth Edition

47. File Management (continued)
Virtual file
Primary file handling concept (current windows)
Programs perform I/O on virtual files
File handles manipulate them
Executive file object representing all sources and destinations of I/O
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
Understanding Operating Systems, Fifth Edition

48. File Management (continued)
File objects
Hierarchical names
Protected by object-based security
Support synchronization
Handled by object services
Opening file
Process supplies file’s name and type of access required
Understanding Operating Systems, Fifth Edition

49. File Management (continued)
File objects bridge gap
Between physical devices’ characteristics and directory structures, file system structures, data formats
Provides memory-based representation of shareable physical resources
Created with new set of handle-specific attributes
Each time process opens a handle
Understanding Operating Systems, Fifth Edition

50. File Management (continued)
Understanding Operating Systems, Fifth Edition

51. File Management (continued)
Understanding Operating Systems, Fifth Edition

52. File Management (continued)
Mapped file I/O
Important feature of I/O system
Achieved by cooperation with 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, Fifth Edition

53. Network Management Networking
Integral to Windows NT-based operating systems
Provides services
User accounts, resource security
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, Fifth Edition

54. MS-NET Microsoft Networks (MS-NET) Three components MS-NET components
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 Windows NT and later versions
Understanding Operating Systems, Fifth Edition

55. MS-NET (continued) 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 that has appropriate file or resource
Network can incorporate multiple redirectors
Understanding Operating Systems, Fifth Edition

56. MS-NET (continued) 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
Used to pass 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, Fifth Edition

57. MS-NET (continued) 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, Fifth Edition

58. MS-NET (continued)
Understanding Operating Systems, Fifth Edition

59. Directory Services Active Directory
Database storing all information types
General-purpose directory service for heterogeneous network
Built entirely around DNS and LDAP
Groups machines into administrative units called 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 to locate objects on the network
Understanding Operating Systems, Fifth Edition

60. Directory Services (continued)
Understanding Operating Systems, Fifth Edition

61. Security Management Windows network operating systems
Provide object-based security model
Security object
Represent any resource in system (file, device, process, program, or user)
Allows administrators to give precise security access
To specific objects in system allowing them to monitor and record how objects used
Windows biggest concern
Aggressive patch management needed
Combat many viruses and worms
Understanding Operating Systems, Fifth Edition

62. Security Basics U.S. Department of Defense
Identified and categorized operating system features
Seven levels of security
Compliance with Class C2 level security
Features in Windows
A secure logon facility
Discretionary access control
Auditing ability
Memory protection
Understanding Operating Systems, Fifth Edition

63. Security Basics (continued)
Multilayered security system
Strives to prevent access by unauthorized users
Password management: first security layer
NTFS: 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 keeps track of who uses files and how
Understanding Operating Systems, Fifth Edition

64. Security Terminology Built-in security Windows uses Kerberos 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 to determine specific access rights given to client
Provides data integrity using various methods
Windows uses Kerberos security
Understanding Operating Systems, Fifth Edition

65. Security Terminology (continued)
Kerberos Security
Authentication, data integrity, data privacy, mutual authentication
Each domain has own Kerberos server
Microsoft implemented standard Kerberos protocol
Microsoft separated users of distributed security services from their providers
Allows support for many options without unusable complexity
Understanding Operating Systems, Fifth Edition

66. Security Terminology (continued)
Understanding Operating Systems, Fifth Edition

67. User Interface Start an application Quit application
Double-click application icon
Select it from Start menu
Quit application
Select Exit from File menu
Click “x” in top-right corner of window
Understanding Operating Systems, Fifth Edition

68. User Interface (continued)
Start Menu
Divides functions into logical groups
Users access common functions
All Programs
Documents, Pictures, Music, and Computer
Control Panel
Help and Support
Search
Understanding Operating Systems, Fifth Edition

69. User Interface (continued)
Understanding Operating Systems, Fifth Edition

70. User Interface (continued)
Windows Task Manager
Open
Pressing and holding the CTRL, ALT, delete keys
User view running applications and processes
Set priorities of each
User views information
Performance, networking, users logged into system
Windows Explorer (standard utility program)
Contains director, file display tools, file-finding tool
Series of pull-down menus
File, Edit, View, Tools, Help, etc.
Understanding Operating Systems, Fifth Edition

71. User Interface (continued)
Understanding Operating Systems, Fifth Edition

72. User Interface (continued)
Understanding Operating Systems, Fifth Edition

73. User Interface (continued)
Networked systems
Identify and access network resources
Folders, printers, connections to other nodes
Command interface
Resembles MS-DOS
Available from most Windows desktops
Keyboard shortcuts: (CTRL+C for copy)
Built-in input methods and fonts for languages
Windows offers an on-screen keyboard
Resource monitor
Understanding Operating Systems, Fifth Edition

74. User Interface (continued)
Understanding Operating Systems, Fifth Edition

75. User Interface (continued)
Understanding Operating Systems, Fifth Edition

76. User Interface (continued)
Understanding Operating Systems, Fifth Edition

77. User Interface (continued)
Understanding Operating Systems, Fifth Edition

78. User Interface (continued)
Understanding Operating Systems, Fifth Edition

79. Summary Current Windows operating systems
Ease-of-use with technical power
Operate network across several platforms
Significant security controls
Allowed inroads to organizations requiring consistent protection
Authentication models support new user interfaces
Implementation of different security architectures
Require aggressive patch management
Target of viruses and worms
Understanding Operating Systems, Fifth Edition