Wednesday, 13 May 2015

45,paper3,J12. A computer system supports 32 bit virtual address as well as 32 bit physical addresses. Since the virtual address space is of same size as that of physical address space, if we want to get rid of virtual memory, which one of the following is true


Options (A) Efficient implementation of multiuser support is no longer possible.
(B) The processor cache can be made more efficient.
(C) Hardware support for memory management is not needed.
(D) CPU scheduling can be made more efficient.
Answer© Hardware support for memory management is not needed.
In computing, virtual memory is a memory management technique that is implemented using both hardware and software. It maps memory addresses used by a program or processor , called virtual addresses, into physical addresses in computer memory. Main storage as seen by a process or task appears as a contiguous address space or collection of contiguous segments. The operating system manages virtual address spaces and the assignment of real memory to virtual memory. Address translation hardware in the CPU, often referred to as a memory management unit or MMU, automatically translates virtual addresses to physical addresses. Software within the operating system may extend these capabilities to provide a virtual address space that can exceed the capacity of real memory and thus reference more memory than is physically present in the computer. Hence hardware is not required.
The primary benefits of virtual memory include freeing applications from having to manage a shared memory space, increased security due to memory isolation, and being able to conceptually use more memory than might be physically available, using the technique of paging.So when we get rid of virtual memory we donot need hardware unit.

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