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
Windows user interfaces
Understanding Operating Systems, 7e

3. Brief History Windows products before 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. 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

5. Understanding Operating Systems, 7e
(table 14.1)
Select Microsoft Windows operating systems. For details about these and other versions, refer to
© Cengage Learning 2014
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
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 potentially 8TB for the user and 8TB for the kernel.
© Cengage Learning 2014
Understanding Operating Systems, 7e

18. Memory Management (cont’d.)
32 bit versions of Windows limited to maximum of 4gb physical memory
64 bit versions of Windows have increased physical memory limits that vary with version:
Windows 7
Starter = 8GB
Home Basic = 8GB
Home Premium = 16GB
Professional = 192GB
Enterprise = 192GB
Ultimate = 192GB Source: zdnet.com
Understanding Operating Systems, 7e

19. User-Mode Features
Some newer versions of Windows have 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
Example: Run Windows XP in Windows 7 (Professional, etc.…)
Understanding Operating Systems, 7e

20. 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

21. 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

22. Processor Management 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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., towson.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

29. 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

30. User Interface GUI - Windows 8 Command-line interface
Offers same default screen
All devices running the operating system
Laptop or desktop users
Can switch between tile-populated Start screen and Desktop screen
Command-line interface
Available from most Windows desktops
Use Help feature: learn a command’s syntax
Understanding Operating Systems, 7e

31. 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

32. 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