Definition of IA-32

(AI-32, x86-32). Instruction set architecture of Intel’s most successful microprocessors.

This is a 32-bit extension to the original x86 processor architecture. This architecture defines the instruction set for the family of microprocessors installed in most of the world’s personal computers.

IA-32 stands for 32-bit Intel Architecture, thus distinguishing itself from its predecessor the 16-bit x86 processor, and from the next 64-bit IA-64 implemented on Itanium microprocessors.

The IA-32 architecture was expanded by AMD in 2003 to natively support 64-bit, creating the x86-64 architecture. The first family of processors to support this architecture (called AMD64), were the AMD K8 family of processors. It was the first time that a company other than Intel had created a major enhancement to the IA-32 architecture.

Intel then had to introduce the modified NetBurst family of processors (initially called IA-32e or EM64T and now simply Intel 64), and which is almost identical to AMD64. x86-64 is backwards compatible with 32-bit without performance loss.

Intel was the creator and the largest supplier of the IA-32 processor, but it is not the only one. It is seconded by AMD and then other smaller companies.

Intel, AMD, and VIA Technologies still produce IA-32 processors, but are moving to the x86-64 architecture.

Brief history of the IA-32 (x86-32)

The IA-32 instruction set was introduced by Intel in the 80386 microprocessors in 1985, and is still used in most processors more than two decades later. However, successive generations of microprocessors made these instructions execute faster.

IA-32 is generally categorized as CISC architecture, however these classifications have become less significant with the advancement of microprocessor design. Most modern x86 architectures (K7, NetBurst, and others) are often classified as post-RISC processors.

Some features of the IA-32 (x86-32)

* Memory management models:

There are two types of memory access models that IA-32 supports. One is called Real Mode and another Protected Mode. In Real Mode, the processor is limited in accessing a total of 1 MB of memory, while in Protected Mode it can access all of its memory (up to 4 GB in one address space).

Real Mode is required by operating systems like DOS, whereas Protected Mode is required by operating systems like Windows, Linux, and OS/2.

* Records:

The 386, and all IA-32 processors, have eight 32-bit general purpose registers for applications in use. AMD64 processors provide 16 registers. Other newer processors added new registers with their own instruction sets like MMX, 3DNow!, SSE, SSE2, SSE3 and SSSE3.

There are also system logs, mostly used by operating systems and not applications.

* Instruction set:

The original IA-32 instruction set has evolved over time with the addition of multimedia instructions. Anyway, the last evolution of the IA-32 was when it was extended to 64 bits, but obviously it couldn’t be called IA-32 anymore. The 64-bit extension was called x86-64.

The first x86-64 instruction set was designed by AMD and called AMD64. It was later imitated by Intel when it released its Intel 64 (formerly IA-32e and EM64T).