Virtual Memory (An extension of main memory) is the most fundamental concept implemented by a system that performs memory management functions such as space allocation, program relocation and code sharing.
Operating systems employ a method of extending RAM capacity, known as “virtual memory”. Virtual memory is a section of volatile memory created temporarily on the storage drive. It is created when a computer is running many processes at once RAM is running low.
Note : 80286 intel first microprocessor to include virtual memory.
Virtual Memory consists of those addresses that generated by a processor during execution. The addresses in virtual memory are called logical addresses. These addresses are dynamically translated into physical addresses at run time. The operating system work together to give each process the illusion that it is the only process running on the computer. Each process has its own set of virtual address spaces, which the MMU translates into actual physical addresses.
Paging/Segmentation System
A frequent method in an operating system for a computer is virtual memory (OS). A process address space is divided into fixed-sized pieces called pages during paging. In segmentation, a process address space is divided into pieces of variable sizes. Key Points In order to make up for actual memory shortages, a computer uses virtual memory, which temporarily moves data from random access memory (RAM) to disc storage. Paging is a storage mechanism used in operating systems to recover processes as pages from secondary storage and place them in main memory. The physical address space of a process can be non-contiguous thanks to segmentation. A user address space may be divided into a number of segments in a combined paging/segmentation system at the programmer’s discretion.
Q. In almost all modern multi programming systems, principal operation of memory management involves a sophisticated scheme known as _______. [SSC Scientific Assistant Computer Science 2017] memory partitioning virtual memory real memory memory organization
Q. Techniques that automatically move program and data blocks into physical main memory when they are required for execution are called : [ISRO Scientist Electrical 2015] (a) Main memory techniques (b) Cache memory techniques (c) Virtual memory techniques (d) Associate memory techniques
Q. _______ is based on the use of one or both of two basic techniques – segmentation and paging. [SSC Scientific Assistant Computer Science 2017] (a) memory partitioning (b) virtual memory (c) real memory (d) memory organization
Virtual Memory is a space where large programs can store themselves in form of pages while their execution and only the required pages or portions of processes are loaded into the main memory. This technique is useful as large virtual memory is provided for user programs when a very small physical memory is there. Additional Information Cache memory is a type of fast, relatively small memory that is stored on computer hardware. Commonly shortened to cache, it is classed as random access memory which computer microprocessors can access more quickly than regular RAM. Read-only memory (ROM) is a type of storage medium that permanently stores data on personal computers (PCs) and other electronic devices. It contains the programming needed to start a PC, which is essential for boot-up; it performs major input/output tasks and holds programs or software instructions. Flash memory is a long-life and non-volatile storage chip that is widely used in embedded systems. It can keep stored data and information even when the power is off. It can be electrically erased and reprogrammed. Flash memory was developed from EEPROM (electronically erasable programmable read-only memory).
Q. is RAM that is stored on a Hard disk by extending portion of its available disk capacity. [OSSC BSSO 2022] (a) Virtual Memory (b) Volatile Memory (c) Non Volatile Memory (d) USB Memory
Virtual memory: It is a feature of an operating system that enables a computer to be able to compensate for shortages of physical memory by transferring pages of data from random access memory to disk storage. This process is done temporarily and is designed to work as a combination of RAM and space on the hard disk. This means that when RAM runs low, virtual memory can move data from it to a space called a paging file. This process allows for RAM to be freed up so that a computer can complete the task. Occasionally a user might be shown a message that says the virtual memory is running low, this means that either more RAM needs to be added, or the size of the paging file needs to be increased. It allows us to have memory protection because each virtual address is translated to a physical address. Virtual memory storage scheme that provides users an illusion of having a very big main memory. Additional Information Computer Memory: All input data, instructions, and data interim to the processes are stored in the memory. Memory is of two types The primary memory The secondary memory. Primary memory resides within the CPU whereas secondary memory is external to it. Virtual memory is an additional memory that is a feature of an operating system.
Q. Virtual memory is [ECGC PO 2021] (a) Large secondary memory (b) Illusion of large main memory (c) Large main memory (d) A type of memory used in super computers
Q. k
The all three statements are correct. The main objective for using virtual memory is indeed to increase the effective capacity of the memory system by allowing programs to operate as if there is more main memory available than is physically installed. The size of the program can be as large as the size of the secondary memory because virtual memory allows a program to run as if the entire operating system’s memory is available to it, while in actuality it may be stored on secondary storage, such as a hard disk drive. With virtual memory, program and data are indeed often stored in secondary memory. They are only loaded into the primary memory (such as RAM) as necessary, which enables efficient memory usage.