B.Ramamurthy Chapter 2 : Appendix Windows NT and Unix OS B.Ramamurthy Chapter 2 : Appendix 1/10/2019 B.Ramamurthy

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) 1/10/2019 B.Ramamurthy

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. 1/10/2019 B.Ramamurthy

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. 1/10/2019 B.Ramamurthy

MicroKernel Microkernel consists of most fundamental components of the operating system. Process control, thread control, context switching, scheduling, synchronization etc. Non pre-emptable. 1/10/2019 B.Ramamurthy

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. 1/10/2019 B.Ramamurthy

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. 1/10/2019 B.Ramamurthy

Traditional Unix System Fig.2.16 System call interface File Subsystem Process Control subsystem Device driver/ IO subsystem Hardware control 1/10/2019 B.Ramamurthy

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.) 1/10/2019 B.Ramamurthy

OS Topics Fig2.18 Memory Management File Management Process Description and Control IO management Security Networking Concurrency Scheduling 1/10/2019 B.Ramamurthy