address space


address space

[′ad·rəs ‚spās] (computer science) The number of storage locations available to a computer program.

address space

(operating system, architecture)The range of addresses whicha processor or process can access, or at which a device canbe accessed. The term may refer to either physical addressor virtual address.

The size of a processor's address space depends on the widthof the processor's address bus and address registers.

Each device, such as a memory integrated circuit, will haveits own local address space which starts at zero. This willbe mapped to a range of addresses which starts at some baseaddress 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 memorythe process happens to have been loaded. For a process to beable to run at any address it must consist ofposition-independent code. Alternatively, each process maysee the same local address space, with the memory management unit mapping this to the process's own part of theprocessor's address space.

address space

A computer's address space is the total amount of memory that can be addressed by the computer. The term may refer to the physical memory (RAM chips) or virtual memory (disk/SSD). For example, a 32-bit computer can address 4GB of physical memory and as much as 64TB of virtual memory. See address register and flat address space.