Operating System Control Structures

If the operating system is to manage processes and resources, then it must have information on the current status of each process and resources. The universal approach to provide this information is as follows: The operating system builds and maintains information boards on each of the entities it manages. The operating system has four functions, and it should be capable of supporting four functions, they are memory, I / O, file and process. Although the details differ from one operating system to another, all operating systems maintain information in these four categories.Memory tables are used to keep track of the two main (real) and secondary ( virtual) memory. Some of the main memory is reserved for use by the operating system, the remainder is available for use by the process. The processes are maintained on a secondary memory with the help of a kind of virtual memory or simply swap mechanism. Tables of memory must contain the following information. The allocation of main memory to process, memory allocation for secondary processes and the attributes of any protection or principal segments of the virtual memory, such as the processes that may have access to certain areas of shared memory. All information needed to manage virtual memory.I / O tables are used by the operating system to manage I / O devices and circuits of computers. At any time, an I / O device may be available or allocated to a particular process. If an I / O is under way, the operating system needs to know the status of the I / O operation and the location in memory is used as the source or destination of the I / O transfer. The operating system may also maintain file tables, which give information about the existence of files, their location on the secondary memory, their present status, and other attributes. Much, if not all of this information can be maintained and used by a management system file, in which case the operating system has little or no grasp of the issues. In other operating systems much of the detail of file management is managed by the operating system itself.Quick Note: Take Nonsense search of good spyware removerIf you really want to take the research of this Right from a Spyware Protection Spybot go to the Internet and to receive free Spybot or a Free Spybot Search and DestroyDownload, To avoid having your vital information from being uprooted from your computer Today.Finally your Spybot Remover, the operating system must maintain processes to manage the process tables. The rest of this section is devoted to a discussion of table process. Tables should be bound or referrals in a certain way. Memory, I / O, and the files are managed on behalf of the operation, there must be a direct or indirect reference to these resources in the process of tables.