Virtual Address - Overview

Overview

Virtual memory is easiest to comprehend if one thinks in terms of the VAS, and not the physical memory of the machine nor the size of its page file. Byte values in the VAS come only from byte values in a file. The OS manages the mapping between the VAS and the files that hold its values.

Each time an application is run on an operating system (OS), the OS creates a new process and a new VAS for this process.

Physical memory comes in various flavors: on-chip cache, off-chip cache, and system memory. As far as the process is concerned, system memory is just another level of cache used by the OS. System memory has a lot to do with performance, but nothing to do with the architecture of a process. The process architecture is based on the VAS. Physical memory is used by the OS to map values from file bytes to VAS addresses: process memory is VAS memory, not physical memory.