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Homework-2 Answers - OPERATING SYSTEMS HOMEWORK - 2 Tapan...

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OPERATING SYSTEMS HOMEWORK - 2 Tapan Shah (ID : 0562363) 10/5/2009
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2.1 What is PCB? Why do we need it? ANS : - A process in an operating system is shows by a data structure known as a process control block (PCB) and also know as Task Control Block . Process State Process number Program Counter Registers Memory limits List of open files …………. . (Process Control Block) Information associated with a specific process is Process state : - The state may be new, ready, running, waiting, halted and so, on. Program counter : - The counter indicates the address of the next instruction to be executed for the process. CPU registers : -Along with program counter, state information must be saved when an interrupt occurs, to allow process to be continued correctly afterward. State information include values of
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accumulators, index registers, stack pointers, and general-purpose registers plus any condition code information. CPU-scheduling information : - CPU-scheduling information includes a process priority, pointers to scheduling queues. Memory-management information : - Memory management information includes value of the base and limit registers, the page tables or the segment tables, depending on the memory used by the operating system. Accounting information : - Accounting information includes the amount of CPU and real time used, time limits, account numbers, job or process numbers, etc. I/O status information : - I/O status information includes the list of I/O devices allocated to the process. And other information such as open files etc. It holds some important information which includes: The current state of the process i.e., status of ready, running, waiting, or whatever. Unique identification of the process in order to track "which is which" information. A pointer to parent process.
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This note was uploaded on 04/19/2010 for the course CS 503.9 taught by Professor Lie during the Spring '10 term at udg.edu.

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Homework-2 Answers - OPERATING SYSTEMS HOMEWORK - 2 Tapan...

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