Windows NT and Unix OS

1
Windows NT and Unix OS

• B.Ramamurthy
• Chapter 2 Appendix

2
Windows NT

• Significance Designed from scratch incorporating
  all the latest technologies available at that
  time.
• Single user, multi-tasking
• Client-server
• SMP Symmetric multiprocessing
• Multi-threading
• Micro-kernel approach
• Object-oriented design
• Graphical User Interface (Windows)

3
Windows NT Architecture Fig.2.13

• NT can execute on a variety of hardware platform
• Posix, Win32, OS/2, etc.
• NT separates the application-oriented software
  from OS software by an elaborate module known as
  NT Executive.
• NT execution operates in the kernel mode.

4
NT Executive

• Highly modular, modified micro-kernel.
• Well-defined API for each module allows easy
  modification of functionality.
• Hardware Abstraction Layer (HAL) maps between
  command s and hardware. DMA, Interrupt
  controller, SMP are supported at this layer.

5
MicroKernel

• Microkernel consists of most fundamental
  components of the operating system.
• Process control, thread control, context
  switching, scheduling, synchronization etc.
• Non pre-emptable.

6
Services

• Executive Services
• IO manager, and Window Manager which directly
  deal with harwdare.
• Object manager, Security, process, virtual
  memory, call manager these modules go thru HAL.
• System Services interface to user-mode software.

7
Object-Oriented Approach

• NT is partially OO.
• Processes, files, threads, semaphores, timers,
  windows are all designed as objects (classes).
• Each object created has a handle (object
  reference) and a security descriptor (SD).
• Many other data structures used are not classes
  or objects.

8
Traditional Unix System Fig.2.16

• System call interface
• File Subsystem
• Process Control subsystem
• Device driver/ IO subsystem
• Hardware control

9
Modern Unix Kernel

• System V release 4 (SVr4)
• Solaris 2.x
• Berkeley Software Distribution (BSD 4.4)
• Core facilities, set of specific
  functionalities (scheduler, vnode interface,
  Virtual memory management, etc.)

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OS Topics Fig2.18

• Memory Management
• File Management
• Process Description and Control
• IO management
• Security
• Networking
• Concurrency
• Scheduling