It is the oldest architecture of the operating system. We know that all the core software components of the operating system are collectively known as the kernel.
31 Aug 2017
31 Dec 2017
The Mach operating system
Mach The Mach operating system traces its ancestry to the Accent operating system developed at Carnegie Mellon University (CMU) (Rashid and Robertson [1981]). Mach's communication system and philosophy are derived from Accent, but many other significant portions of the system (for example, the vir...
29 Dec 2017
Stateful Versus Stateless Service
Stateful Versus Stateless Service There are two approaches for storing server-side information when a client accesses remote files: Either the server tracks each file being accessed byeach client, or it simply provides blocks as they are requested by the client without knowledge of how those block...
31 Dec 2017
Event Ordering
Event Ordering In a centralized system, we can always determine the order in which two events occurred, since the system has a single common memory and clock. Many applications may require us to determine order. For example, in a resourceallocation scheme, we specify that a resource can be used on...
24 Dec 2017
Threads overview
A thread is a basic unit of CPU utilization; it comprises a thread ID, a program counter, a register set, and a stack. It shares with other threads belonging to the same process its code section, data section, and other operating-system resources, such as open files and signals. A traditional (or h...
27 Dec 2017
Copy on write
Copy-on-Write we illustrated how a process can start quickly by merely demandpaging in the page containing the first instruction. However, process creation using the fork () system call may initially bypass the need for demand paging by using a technique similar to page sharing (covered in Section...
24 Aug 2017
Operating System Concepts ( Multi tasking, multi programming, multi-user, Multi-threading )
Operating system acts as an interface between the user and the hardware. It is something which relieves the user from bothering about hardware related issues. what is multitasking, Multiprogramming, Multiuser Operating System, Multithreading
31 Aug 2017
Microkernel Architecture of operating system
The basic ideology in this architecture is to keep the kernel as small as possible. We know that kernel is the core part of the operating system and hence it should be meant for handling the most important services only.
31 Aug 2017
Layered Architecture of Operating System
This is an important architecture of operating system which is meant to overcome the disadvantages of early monolithic systems.
01 Jan 2018
Types of System Calls
Types of System Calls System calls can be grouped roughly into five major categories: process control, file manipulation, device manipulation, information maintenance, and communications. In Sections 2.4.1 through 2.4.5, we discuss briefly the types of system calls that may be provided by an opera...
31 Aug 2017
Hybrid Architecture of Operating System
the idea was to combine the best functionalities of all old approaches and hence this design is termed as the hybrid structured operating system.
31 Aug 2017
System Programs and Calls
System Calls and Programs All the present-day operating systems support the following two modes of operation for the CPU: User mode Kernel mode
User Operating-System Interface There are two fundamental approaches for users to interface with the operating system. One technique is to provide a command-line interface or command interpreter that allows users to directly enter commands that are to be performed by the operating system. The seco...
31 Aug 2017
Architectures of Operating System
there are 4 types of architectures of operating system: 1. Monolithic architecture 2. Layered architecture 3. Microkernel architecture 4. Hybrid architecture
26 Dec 2017
Systems Analysis and Design: Core Concepts
Goal of systems analysis and design is to improve organizational systems. This process involves developing or acquiring application software and training employees.
24 Dec 2017
Operating System Generation
It is possible to design, code, and implement an operating system specifically for one machine at one site. More commonly, however, operating systems are designed to run on any of a class of machines at a variety of sites with a variety of peripheral configurations. The system must then be configur...
24 Dec 2017
Operations on Process
The processes in most systems can execute concurrently, and they may be created and deleted dynamically. Thus, these systems must provide a mechanism for process creation and termination. we explore the mechanisms involved in creating processes and illustrate process creation on UNIX and Windows sy...
29 Dec 2017
Revocation of Access Rights
Revocation of Access Rights In a dynamic protection system, we may sometimes need to revoke access rights to objects shared by different users
23 Dec 2017
Process Scheduling
Process scheduling selects processes from the queue and loads them into memory for execution. Process loads into the memory for CPU scheduling. The primary objective of the job scheduler is to provide a balanced mix of jobs, such as I/O bound and processor bound. ... Time-sharing operating systems ...
24 Dec 2017
Multithreading Models
Our discussion so far has treated threads in a generic sense. However, support for threads may be provided either at the user level, for user threads, or by the kernel, for kernel threads. User threads are supported above the kernel and are managed without kernel support, whereas kernel threads are ...
25 Dec 2017
File concept
File Concept Computers can store information on various storage media, such as magnetic disks, magnetic tapes, and optical disks. So that the computer system will be convenient to use, the operating system provides a uniform logical view of information storage. The operating system abstracts from ...
25 Aug 2017
Network Operating System
Network Operating System is a collection of various computers which are all connected to a single host computer. It can be compared to a client – server architecture where the host computer acts as a server and rest of the systems act as clients which take services from the common server and access ...
30 Dec 2017
Multiprocessor Scheduling
Multiple-Processor Scheduling Our discussion thus far has focused on the problems of scheduling the CPU in a system with a single processor. If multiple CPUs are available, load sharing becomes possible; however, the scheduling problem becomes correspondingly more complex. Many possibilities hav...
27 Dec 2017
Disk Attachment
Disk Attachment Computers access disk storage in two ways. One way is via I/O ports (or host-attached storage); this is common on small systems. The other way is via a remote host in a distributed file system; this is referred to as network-attached storage.
Computing Environments : Traditional Computing, Client-Server Computing, Peer-to-Peer Computing, Web-Based Computing
25 Aug 2017
Batch Operating Systems
The main function of a batch processing system is to automatically keep executing the jobs in a batch. This is the important task of a batch processing system i.e. performed by the 'Batch Monitor' resided in the low end of main memory. This technique was possible due to the invention of hard-disk dr...
27 Dec 2017
Thread Libraries
Thread Libraries A thread library provides the programmer an API for creating and managing threads. There are two primary ways of implementing a thread library. The first approach is to provide a library entirely in user space with no kernel support. All code and data structures for the library ex...
31 Aug 2017
Various Operating system services
We can broadly classify these services into following five categories: Process management Device management Inter-process Communication File management Error detection
01 Jan 2018
Introduction to Protection and Security
Protection and Security If a computer system has multiple users and allows the concurrent execution of multiple processes, then access to data must be regulated. For that purpose, mechanisms ensure that files, memory segments, CPU, and other resources can be operated on by only those processes tha...
23 Dec 2017
System Boot
After an operating system is generated, it must be made available for use by the hardware. But how does the hardware know where the kernel is or how to load that kernel? The procedure of starting a computer by loading the kernel is known as booting the system.
