Question

Computer architecture

Question 26 What is a required feature in order to implement the virtual memory? (check all that are true) Physical address space larger than virtual address space Assembly instructions to go back and forth between user mode and kernel mode A multicore CPU The use of an Operating System (OS) An ISA that supports at least two privilege levels.

Answer 1

Answer :

• Physical address space larger than logical address space in virtual memory
• The use of an operating system

Explanation :

Virtual Memory is a storage allocation scheme in which secondary memory can be addressed as though it were part of main memory. The addresses a program may use to reference memory are distinguished from the addresses the memory system uses to identify physical storage sites, and program generated addresses are translated automatically to the corresponding machine addresses.
The size of virtual storage is limited by the addressing scheme of the computer system and amount of secondary memory is available not by the actual number of the main storage locations.

It is a technique that is implemented using both hardware and software. It maps memory addresses used by a program, called virtual addresses, into physical addresses in computer memory.

1. All memory references within a process are logical addresses that are dynamically translated into physical addresses at run time. This means that a process can be swapped in and out of main memory such that it occupies different places in main memory at different times during the course of execution.
2. A process may be broken into number of pieces and these pieces need not be continuously located in the main memory during execution. The combination of dynamic run-time address translation and use of page or segment table permits this.