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Deadlock

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  DEADLOCKS: The deadlock is a situation, It the resource is not available when it is requested, the requesting process is forced to wait. In some operating system, the process is automatically blocked when a resource request fails and awakened when it becomes available. A deadlock is situation where groups of process are presently blocked in computer. Following is Graphical Presentation of A DEADLOCK. The above figure shows square boxes as resources named R1 and R2. Similarly, processes shown as circles are named P1 and P2.  The arrow shows the relationship for example in part (a-1) of the figure, resources R1 is allocated to process p1. or in other words P1 holds R1. In part (b-1) of the figure, process P2 wants resources R2, but it has not got it, it is waiting for it. These graphs are called ‘Directed Resource Allocation Graphs (DRAG) Now see the following situation for the deadlock. P1 holds R1 but demands R2 P2 holds R2 but demands R1 It we draw the directed resourc...

Type of Operating System

 Operating Systems:  DOS Windows Based 

Layered Systems

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  Layered Systems: In the layered system structure, operating system is organized as hierarchy of layers, each of the layers is constructed upon one another. The first system constructed in this way was the THE system built at the Technische Hogeschool Eindhoven in the Netherlands by E. W. Dijkstra and his students. The THE system was a simple batch system for a Dutch computer. Layer 0 assign with allocation of the processor, switching between processes when timers expired.    Above layer 0, the system consisted of sequential processes, each of which could be programmed without having to worry about the fact that multiple processes were running on a single processor. In other words, layer 0 provided the basic multiprogramming of the CPU. Layer 1 was used to the memory management. It distributed space for processes in main memory used for holding parts of processes. Layer 1 was taking care of making sure pages are transport into memory whenever they are needed....

Monolithic Operating System

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Monolithic Operating   System: A monolithic an operating system architecture where the entire operating system is working in kernel space. The monolithic model differs from other operating system architectures. The monolithic operating system is a very basic operating system in which file management, memory management, device management, and process management are directly controlled within the kernel.   Monolithic system is also known as simple system. This approach the entire operating system runs as a single program in kernel mode. The operating system is written as a collection of procedures, linked together into a single large executable binary program. When this technique is used, each procedure in the system is free to call any other one, if the latter provides some useful computation that the former needs. Having thousands of procedures that can call each other without restriction.             To construct ...

Services Provided by Operating System

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Services Provided by Operating System: An operating system provides an environment for the execution of user programs. It provides certain services to programs and to the users of those programs. The specific services provided, of course, differ from one operating system to another operating system. These operating system services are provided for the convenience of the programmer, to make the programming task easier and more efficiently. The following diagram is shows various operating system-                                Figure: Operating System Services These are the following services provided by operating system- User Interface : Almost all operating systems have a user interface. This interface can take several forms. One is a command-line interface, which uses text commands and a methods for entering them. Another is a batch interface, in which commands and di...

operating system components

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Operating System components : An Operating system is an interface between users and the hardware of a computer system. It is system software that is viewed as an organized collection of software consisting of procedures and functions, providing an environment for the execution of programs. The operating system manages resources of system software and computer hardware resources. It allows computing resources to be used in an efficient way. Programs interact with computer hardware with the help of operating system. These are the important component of operating system as follows:               Process Management: The operating system manages many types of activities ranging from user programs to system programs like printer spoiler, name servers, file server etc. Each of these activities is summarize in a process. The five major activities of an operating system in regard to process management are : Creation and deletion of user and sys...