In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, a logical address is the address at which an item (
memory cell, storage element, network host) appears to reside from the perspective of an executing
application program
Application may refer to:
Mathematics and computing
* Application software, computer software designed to help the user to perform specific tasks
** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...
.
A logical address may be different from the
physical address due to the operation of an
address translator or mapping function. Such mapping functions may be, in the case of a
computer memory architecture, a
memory management unit
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical a ...
(MMU) between the
CPU
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, a ...
and the memory bus.
Computer memory
The physical address of computer memory banks may be mapped to different logical addresses for various purposes.
In a system supporting
virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very ...
, there may actually not be any physical memory mapped to a logical address until an access is attempted. The access triggers special functions of the operating system which reprogram the MMU to map the address to some physical memory, perhaps writing the old contents of that memory to disk and reading back from disk what the memory should contain at the new logical address. In this case, the logical address may be referred to as a
virtual address.
See also
*
Memory segment
*
Flat memory model
Flat memory model or linear memory model refers to a memory addressing paradigm in which "memory appears to the program as a single contiguous address space." The CPU can directly (and linearly) address all of the available memory locations witho ...
*
Memory address
In computing, a memory address is a reference to a specific memory location used at various levels by software and hardware. Memory addresses are fixed-length sequences of digits conventionally displayed and manipulated as unsigned integers. ...
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Virtual memory