1.When packets of information in predefined formats are moved between processes by the operating system,you can use message passing.
Advantages of the Message Passing Model: One of the biggest semantic advantages of themessage-passing communication model is the fact that it is, by nature, interrupt driven. Messages combine both data and synchronization in a single unit.
Disadvantages of Message Passing: In addition to requiring the explicit management of data and communication, the message passing paradigm has one intrinsic disadvantage that can be mitigated but not eliminated by good interface design: the presence of higher endpoint costs in message passing models as compared to shared memory.
Advantages of the Shared Memory Model:. One of the primary reasons for this is that shared memory shelters programmers from the details of interprocessor communication: the location-independent semantics of shared memory allow programmers to focus on issues of parallelism and correctness while completely ignoring issues of where data is and how to access it. This can allow the “quick construction” of algorithms that communicate implicitly through data structures. In some sense, the shared-memory communication model offers one of the simplest extensions of the uniprocessor programming paradigm to multiprocessors
Disadvantages of Shared Memory: One of the deficiencies of the shared-memory communication model is the fact that it is, by nature, a polling interface. While this can make for extremely efficient communication under some circumstances, it can have a negative impact on synchronization operations.
2.System call provide the interface between a running program and the operating system. System call is available to the operating system used by the application function call. Usually the system call will cause the system transferred to the program executed in kernel mode. System call is to allow the operating system to make smooth.
3.Hardware configuration information can be used in different ways. First, construct a system that is completely table driven. All the code is always part of the system, and selection occurs at execution time. Second , used to create tables and modules from a precompiled library. The needed modules are linked together to form the generated OS. Third, used to modify a copy of the source code of the OS and have it re-compiled. Hardware configuration references the details and system resource settings allotted for a specific device. Many computer specialists improve hardware performance by adjusting configurations, which may also include settings for the motherboard and the BIOS, as well as the bus speeds. System generation is a process that creates a particular and uniquely specified operating system; it combines user-specified options and parameters with manufacturer-supplied general-purpose or non-specialized program subsections to produce an operating system (or other complex software) of the desired form and capacity. And the major differences among above is the size and generality of the generated system and the ease of modification as the hardware configuration changes.