Computer Science – Data storage | e-Consult

Virtual memory is a memory management technique that gives programs the illusion of having more memory than is physically available in the computer's RAM. It achieves this by using a portion of the hard disk (or SSD) as an extension of RAM. The operating system (OS) plays a crucial role in managing this process.

Here's how it works:

• Address Spaces: Each program gets its own virtual address space, a range of addresses that the program believes it can access. This is separate from the physical memory addresses.
• Paging: The virtual address space is divided into fixed-size blocks called pages. Physical memory is also divided into equally sized blocks called frames.
• Page Table: The OS maintains a page table for each process. This table maps virtual pages to physical frames. If a virtual page is not currently in RAM, the page table entry will indicate that it's stored on the hard disk.
• Page Fault: When a program tries to access a virtual page that isn't in RAM (a page fault), the OS intercepts the request. It then retrieves the required page from the hard disk and loads it into a free frame in RAM. The page table is updated to reflect the new location of the page.

Benefits of Virtual Memory:

• Allows running larger programs: Programs can be run even if they require more memory than is physically available.
• Multitasking: Multiple programs can run concurrently, each with its own virtual address space, without interfering with each other.
• Memory Protection: Each process has its own isolated address space, preventing one program from accidentally or maliciously accessing the memory of another.
• Efficient Memory Utilization: Only the parts of a program that are currently being used need to be loaded into RAM.