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 managementunit mapping this to the process's own part of the

processor's address space.

(1999-11-01)