分类： LINUX
2008-05-30 17:13:59
IA-32 (Intel Architecture, 32-bit),
sometimes generically called x86-32, is the of 's most
commercially successful . This is a extension of
the original Intel
processor architecture. This architecture defines the for the family of microprocessors installed in the vast majority of in the world.
IA-32 is Intel's 32-bit implementation of the , distinguished from the preceding x86
processors, and the later architecture implemented in
the
microprocessors. IA-32 has had such longevity partially because of full
backwards compatibility.
The IA-32 instruction set is usually described as a CISC ()
architecture, though such classifications have become less meaningful with
advances in microprocessor design. Most modern x86 architectures (, and
newer) are often referred to as post-RISC processors.
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Contents [] |
[] History
The IA-32 instruction set was introduced in the
microprocessor in
and remains the basis of most PC microprocessors over twenty years later. Even
though the instruction set has remained intact, the successive generations of
microprocessors that run it have become much faster. Within various directives, IA-32 is
still sometimes referred to as the "i386" architecture.
Intel was the inventor and is the biggest supplier of IA-32 processors,
but it is not the only supplier. The second biggest supplier is AMD. There are
other suppliers, but their volumes are small. As of 2007, Intel is moving to
x86-64, but still produces IA-32 processors such as
for laptops. continues to produce the /C7 family
of "pure" IA-32 devices, and AMD still produces the line and mobile IA-32 processors. For a
time
produced IA-32 processors.
The IA-32 architecture was expanded by in 2003 to natively support 64 bits,
creating a new derivative architecture. The first family of processors to support
this architecture, which AMD calls AMD64, was the family of
processors. This was the first time any company other than Intel made
significant additions to the IA-32 architecture. Intel was forced to follow
suit, introducing modified family processors, initially referred to as
"IA-32e" or "EM64T" and now called Intel 64 and almost
identical to AMD64. x86-64 is backwards compatible with 32-bit code without any
performance loss. For example, The Developers Manuals available from Intel on
the IA-32 architecture refer to IA-32 and IA-32e in tandem.
[] Succeeding
architectures
The original IA-32 instruction set has been evolved over time with the
addition of the multimedia instruction updates. Many new architectures,
including 64-bit ones, have since succeeded IA-32. However, the ultimate
evolution of IA-32 was when it was extended again to 64-bits, but of course at
that point it cannot be called IA-32 anymore; the 64-bit extension is called . It could
not be called
as Intel had already used this label for the design (a
design which is not really an evolution of the IA-32 architecture). AMD's was the first
x86-64 instruction set designed. Later, Intel followed by imitating AMD's
design with what they call (formerly IA-32e and EM64T).
[] IA-64
Main article:
Intel's IA-64 architecture is not directly compatible with the IA-32
instruction set, despite having a similar name. It completely discards all
IA-32 instructions, and starts from scratch with a completely different
instruction set as well as using a design instead of out-of-order execution. IA-64 is the
architecture used by the line of processors. Itanium initially had
hardware-support for IA-32, but it was very slow. Intel shifted to the use of a
software
instead. The nomenclature "IA-64" means "Intel Architecture,
64-bit", but the connection with IA-32 is only in the name.
Further improvements are:
[] AMD64
Main article:
's AMD64
instruction set, initially called x86-64, is largely built on top of IA-32, and
thus maintains the
family heritage, despite having a different name. While extending the
instruction set, AMD took the opportunity to clean up some of the odd behavior
of this instruction set that has existed since its earliest 16-bit days, while
the processor is operating in 64-bit mode.
Further improvements are:
[] Intel 64
Main article:
By February 2004, Intel announced the
instruction set, formerly known as . It was
derived from AMD's .
Intel 64 is generally compatible with code written for the AMD64, though it
lacks some AMD64 features. Intel started using the set starting with the Nocona core in
late 2004, introducing it to the desktop market with the
E0 revision in early 2005.
[] See also
[] External links
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