address space (operating system, architecture) The range of addresses which a processor or process can access, or at which a device can be accessed. The term may refer to either physical address or virtual address.
The size of a processor's address space depends on the width of the processor's address bus and address registers. Each device, such as a memory integrated circuit, will have its own local address space which starts at zero. This will be mapped to a range of addresses which starts at some base address in the processor's address space. Similarly, each process will have its own address space, which may be all or a part of the processor's address space. In a multitasking system this may depend on where in memory the process happens to have been loaded. For a process to be able to run at any address it must consist of position-independent code. Alternatively, each process may see the same local address space, with the memory management unit mapping this to the process's own part of the processor's address space. Last updated: 1999-11-01
