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Comparison between real time and time sharing operating system

Protection and security

• Protection refers to a mechanism for controlling the access of program s processes, or users to the resources defined by computer system.

• The concept of protection came with the advent of multiprogramming where several processes compete for the use of CPU.

• the purpose was to confine each users program to its assigned areaof memory so that the programs cannot interface and harm each other.

• Protection in main memory is particularly important because of address translation. The purpose of protection is to allow concurrently running process to share the common physical address space.

• Protection also ensure that only process that have gained proper authorization from the operating system can operate on memory segment , the CPU, files and other resources.

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Defination of OS(operating system) and its concepts

What do you mean by operating system? Definition : An operating system is a program that act as an interface between the user of a computer and the Computer hardware. Operating system is a first program that gets loaded into the memory through a process called booting. Concepts of operating system : · The purpose of operating system is to provide an environment in which a user can execute program in a convenient and efficient manner. · Operating system is an integrated set of program that ma...

Process Termination or destroy a process

Process Termination or destroy a process Processes may request their own termination by making the exit( ) system call, typically returning an int. This int is passed along to the parent if it is doing a wait( ) , and is typically zero on successful completion and some non-zero code in the event of problems. child code: int exitCode; exit( exitCode ); // return exitCode; has the same effect when executed from main( ) parent code: pid_t pid; int status pid = wait( &status ); // pid indicates which child exited. exitCode in low-order bits of status // macros can test the high-order bits of status for why it stopped Processes may also be terminated by the system for a variety of reasons, including: The inability of the system to deliver necessary system resources. In response to a KILL command, or other un handled process interrupt. A parent may kill its children if the task a...

Application Of Threads

Application Of Threads This section discuss various implementation of threads. Multithreading concepts are implemented by pthread (POSIX standard), solaris, linux, window 2000 and java. 1. POSIX THREAD(Pthreads) · Pthread refers to the POSIX standard(IEEE 1003.IC) that defines an API for thread creation and sychronisation. · Prior to the of POSIX THREADS, each hardware vendor implemented their own version of threads. · As each implemented from the other, writing portable multithreaded application was difficult. Thus POSIX standardize the API for thread management. · The current Pthread API is defined only for C programming language and it is implemented as function with a header file Pthread.h and thread library. · The naming...

Multi processing system

Multi processing system · Multi processesor system is the sytem that contain two or more processors or CPUS and has ability to simultaneously execute several programs. Hence the name multi-processor In such a system, multiple processor share the clock, bus, memory and peripheral devices. · A multi processor system is also known as parallel system · Multi processor system are categorized into two different types: single user operating system 2. Multi user operating system 3. Batch processing operating system 4. Multi programming operating system 5. Multi tasking operating sy...

Multi Programming Operating System

Multi programming system · Multi programming operating system allows multiple users to execute multiple programs using a single CPU concurrently i.e. at the same time. · In multiprogramming several process are kept in the main memory and CPU execute all these processes concurrently. It means, the CPU immediately switches from one process to next that are ready to get executed · In such an operating system when one process start process start performing the instructions from several programs at the same time. · Rather, it means that there are number program available to CPU and that portion of one is executed, then segment of another and so on ...