The general organization diagram of the virtual memory is shown in the figure below. without any programmer's actions) fetches to the main memory data and instructions requested by currently executed programs. It is done under the supervision of the MMU (memory management unit) that governs the real current placement of data determined by virtual addresses. In reality, data and instructions are stored both in the main memory and in the external disk (usually hard disk). Data and instructions are placed in this space with the use of virtual addresses. Virtual memory provides a computer programmer with an addressing space many times larger than the physically available addressing space of the main memory. What is Virtual Memory and how is it implemented? So, can we give each program its own virtual memory space? If so, we can map each program's memory space to the RAM memory space and even move it to the disk if we run out of space. How do we solve this? the key problem here is the same memory space for each program. Can run out of space if we run multiple programs.Can crash if less than 4GB of RAM memory in the system.If all the program have access to same 32-bit memory space ![]() What if program access the same address? - Considering the above image, what if program 1 and program 2 wants to access the same address? For Ex: program 1 stores some data at address lets say 0x1000, and program 2 also stores some data at the same address if the virtual memory technique is not implemented they end up corrupting each other's data. ![]() Virtual memory technique takes care of this using address mapping (we will talk about this later).ģ. Although, we have 2 GB memory left for program 3, it can not be loaded because of the holes created in address space. When the processor is done with the execution of program 1, it removes the program 1 from RAM.
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