Ans: BSD (originally: Berkeley Software Distribution) refers to the particular version of the UNIX operating system that was developed at and distributed from the University of California at Berkeley. "BSD" is customarily preceded by a number indicating the particular distribution level of the BSD system (for example, "4.3 BSD"). BSD UNIX has been popular and many commercial implementations of UNIX systems are based on or include some BSD code.
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Ans: No Windows NT is not so, because its not implemented in object oriented language and the data structures reside within one executive component and are not represented as objects and it does not support object oriented capabilities.
Ans: It does not have the features like ability to support multiple processors virtual storage source level debugging
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Ans: Reasons for Process Suspension:
Ans: Those are application specific and therefore are not defined on the OS level.
Ans: The complete list of changes made to OpenBSD 4.2 to create OpenBSD 4.3 can be found on plus43.html, and highlights on the OpenBSD 4.3 Information page, however here are a few changes the OpenBSD team anticipate will require or warrant some special note to people upgrading or installing OpenBSD 4.3 who are familiar with older versions.
Ans: People often ask why a particular product is or isn't included with OpenBSD. The answer is based on two things: the wishes of the developers and compatibility with the goals of the project. A product will not be included simply because it is "neat" -- it must also be "free" for use, distribution and modification by our standards. A product must also be stable and secure -- a bigger version number does not always mean a better product.
Ans: % chsh -s /usr/local/bin/bash
Ans: SIGTERM asks the application to terminate in a polite way, it warns about the pending closure and asks the app to finish whatever it is doing. SIGKILL will kill the process no matter what. This is telling the application that it will be shut down no matter what.
Ans: The operating system must be able to keep track of the various active processes.
The operating system must allocate and de-allocate various resources for each active process.
The operating system must protect the data and physical resources of each process against unintended interference by other processes. This involves techniques that relate to memory, files, and I/O devices.
The results of a process must be independent of the speed at which the execution is carried out relative to the speed of other concurrent process.
Ans: Concurrency may arise in three different contexts.
Ans: Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request.
External Fragmentation: External Fragmentation happens when a dynamic memory allocation algorithm allocates some memory and a small piece is left over that cannot be effectively used. If too much external fragmentation occurs, the amount of usable memory is drastically reduced. Total memory space exists to satisfy a request, but it is not contiguous.
Internal Fragmentation: Internal fragmentation is the space wasted inside of allocated memory blocks because of restriction on the allowed sizes of allocated blocks. Allocated memory may be slightly larger than requested memory; this size difference is memory internal to a partition, but not being used.
Ans: Once it detects thrashing, what can the system do to eliminate this problem? - Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of multiprogramming.
Ans: OpenBSD is maintained by a development team spread across many different countries. The project is coordinated by Theo de Raadt, located in Canada.