| slovo | definícia |
address space
(foldoc) | address space
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)
|
| | podobné slovo | definícia |
flat address space
(foldoc) | flat address space
The memory architecture in which any memory
location can be selected from a single contiguous block by a
single integer offset.
Almost all popular processors have a flat address space, but
the Intel x86 family has a segmented address space. A
flat address space greatly simplifies programming because of
the simple correspondence between addresses (pointers) and
integers.
(1996-09-10)
|
linear address space
(foldoc) | linear address space
A memory addressing scheme used in processors where the whole
memory can be accessed using a single address that fits in a
single register or instruction. This contrasts with a
segmented memory architecture, such as that used on the
Intel 8086, where an address is given by an offset from a
base address held in one of the "segment registers". Linear
addressing greatly simplifies programming at the {assembly
language} level but requires more instruction word bits to be
allocated for an address.
(1995-02-16)
|
memory address space
(foldoc) | memory address space
1. Any part of a processor's address space
that is occupied by memory.
2. The range of addresses seen by a memory device relative to
the base address at which it is mapped into the processor's
address space.
(1999-11-01)
|
segmented address space
(foldoc) | segmented address space
An addressing scheme where all memory
references are formed by adding an offset to a base address
held in a segment register.
The effect is to segment memory into blocks, which may overlap
either partially or completely, depending on the contents of
the segment registers but normally they would be distinct to
give access to the maximum total range of addresses. In this
case the scheme does provide some degree of {memory
protection} within a single process since, for example, a data
reference cannot affect an area of memory containing code.
However, compilers must either generate slower code or code
with artificial limits on the size of data structures.
The best known implementation is that used on the Intel 8086
and later Intel microprocessors, where a 16-bit offset is
added to a 16-bit base address held in one of four segment
base registers. Each instruction has a default segment (code
(CS), data (DS), stack (SS), ? (ES)) which determines which
segment register is used. Special prefix instructions allow
this default to be overridden.
Other computers, such as GE-645/Honeywell Multics,
Burroughs large systems (B-5500, B-6600), and others,
have used segmentation to good effect.
Opposite: flat address space. See also addressing mode.
[In what way were the others better than Intel's {brain
damaged} implementation?].
(2004-06-01)
|
|