Essential Computer Hardware

Virtual Memory

Virtual Memory is a storage abstraction combining physical RAM and the hard disc creating one large virtual address space for programs to use. In other words, the operating system uses a portion of the hard disc drive as if it were part of the computer’s physical memory (or RAM). This means that programs can be much larger than the physical memory installed.

The problem is, the hard disc drive is much slower than the physical memory (RAM) and has an adverse affect on system performance, since the processor has to wait for data to arrive from the hard disc drive. This is why increasing the physical memory (RAM) increases performance and reduces the need for virtual memory.

Now as with the paging approach, the program’s address ...