Notes on Operating Systems
نویسنده
چکیده
ions A process is essentially an abstraction of a computer. This is one of the major abstractions provided by multiprogrammed operating systems. It provides the operating environment for applications, which is based on the hardware, but with some changes such as lack of access to privileged instructions. But the important point is the isolation from other applications, running as other processes. Each one only sees its own resources, and is oblivious to the activities of the others. Another important abstraction is that of a thread. This actually breaks the process abstraction into two parts: the treads, which can be viewed as an abstraction of the CPU and the flow of the computation, and the process, which abstracts the environment including the address space, open files, etc. For single-threaded processes the distinction is of course moot, and we can say that the process abstracts the whole computer.
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