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.(1999-11-01)