X86

The x86 family groups the microprocessors compatible with the Intel 8086 instruction set. Therefore, x86 represents that instruction set, being also a generic denomination given to the corresponding microprocessors.

Overview

The architecture is notoriously unclean, maintaining compatibility with Intel's line of 16-bit processors, which in turn were also compatible with a family of 8-bit processors. Despite this, the commercial popularity of this architecture caused many manufacturers to start mass-producing compatible microprocessors. Some of these companies are AMD, Cyrix, NEC Corporation, and Transmeta.

There are two 64-bit successors to this architecture:

• IA64, used in Intel Itanium processors and not compatible with X86, except under emulation.
• AMD64 or x86-64, AMD, which is basically a 64-bit extension of the x86 family.

Technically, the architecture is called IA32 (Intel Architecture 32-bit). It is based on a CISC (Complex Instruction Set Computing) architecture model.

History

Intel

Intel began operations as a manufacturer of computer memory. In 1971 it was the first company to achieve the integration of enough transistors to sell a complete programmable microprocessor with a 4-bit instruction set, which would become very common in pocket calculators: The Intel 4004.

The 4004 was succeeded by the 8008 in 1972 and in 1974 by the 8080, each time achieving greater capacity. In 1978, Intel began shipping the 8086 processor, an ambitious 16-bit chip potentially capable of being the heart of multipurpose computers. The 8086 was marketed in versions from 4.77 and up to 10 MHz.

IBM adopted the younger brother of the 8086 (the 8088, a processor with an internal 16-bit data bus, but with the external 8-bit bus, allowing it to take advantage of designs and circuitry for 8-bit systems) to build upon. in it and launch the most successful line of computers in history: the IBM PC (1981) and the IBM XT (eXtended Technology) (1983) (see influence of the IBM PC).

The success of this series was such that from then on, all Intel CPUs maintained a strict backward compatibility policy - Every CPU manufactured by Intel from then until 2021 is capable of running code compiled for any of their predecessors.

The 8086 was succeeded by the 80286 in 1982 (on which the IBM PC/AT was based, 1985). This 24/16-bit chip implemented protected execution mode, laying the groundwork for the emergence of true desktop multitasking systems. The 80286 appeared at 6 MHz, and over the years it went as high as 12 MHz. There were several operating systems that took advantage of their protected mode to offer real multitasking, such as the first versions of OS/2, or Xenix.

But the real multitasking boom didn't come until the birth of the 80386 (1985) - an advance so strong that today it's common to refer to the entire line of processors that followed as i386 (The reference IA32, Intel Architecture of 32 bits, is also common.) The 386 was Intel's first 32-bit processor, and - great news for developers - using it for multitasking applications would already be much easier than it was with the 80286. The 80386 handles speeds from 16 to 33 MHz.

The 80486 appeared in 1989. It was a relatively minor change from the 80386 - Until its introduction, all PC computers had the option of installing a -rather expensive- numerical coprocessor in a motherboard socket - for the XT, the 8087. For the AT, the 80287. For the 386, the 80387. Starting with the 80486, the numerical coprocessor as well as the L1 or level 1 cache were integrated into the CPU chip (the coprocessor only on the 486DX models, 486SX models had it disabled), resulting in a large increase in perceived speed by users. Internally this processor is the first x86 pipelined (with depth 5). This change is important as it allows the same clock rate to execute almost twice as many instructions (1.9) and increase the clock rate. The 486 exists in versions from 20 to 100 MHz. The latter are called 486-DX4 despite multiplying by three the internal operating frequency with respect to the external data bus.

In 1993 the Pentium came out. The 80586 nomenclature was not followed because many competitor companies to Intel had started producing CPUs with the same number as Intel's. Given the fact that a number cannot be used as a trademark, the processors carry their own name. This processor incorporated many novelties, among them a greatly improved coprocessor and a double "prefetch" system, which allowed it to execute two instructions simultaneously in certain situations, with the consequent increase in performance (this was only possible under certain very strict combinations of instructions, so that the performance increase was only noticeable in applications compiled specifically for it). The Pentium went from 60 to 233 MHz.

Shortly after, the Pentium Pro appeared, a server-oriented version that included the second-level cache in the same package as the processor. Its high price put a brake on its expansion, but then its P6 architecture was used for the Pentium II.^{[citation needed]}

Since then, the trend with the Pentium II (1997), Pentium III (1999), and Pentium 4 (2000) releases has been to integrate more components, add multimedia-specific instructions, and raise the clock speed both as possible. The Pentium II came from 233 to 450 MHz. The Pentium III from 450 to 1400 (1.4 GHz). The Pentium 4 debuted at 1.3 GHz and in November 2005 it already reached 3.80 GHz. However, the MHz race was slowed due to the increasing power consumption and heat generation produced by microprocessors at high speeds. clock frequencies, which in recent Pentium 4s easily exceeded 100 W.

Parallel to the Pentium II, two families of CPUs were announced: the Celeron, which is similar to the Pentium but with less cache memory and, consequently, lower price and performance, and the Xeon, oriented to servers, with more cache memory - and of course, much more expensive. The Celerons continued a trend, already started in the 386 and 486, of having two models with different features in the same family of processors: the DX models (386DX and 486DX), with higher features, and the SX models (386SX and 486SX) with lower benefits. In the case of the 386SX for having a 16-bit external bus instead of the 32-bit of the 386DX, and in the 486SX for having the internal math coprocessor disabled. Thus, in the Pentium II, Pentium III and Pentium 4 their corresponding low-cost and performance versions appeared (basically, as has already been said, because they have less level 2 cache memory) under the commercial name of Celeron. It seems that the main reason for this diversification, apart from increasing the range of models, features and prices at a minimum cost, is marketing: due to the constant price drops experienced by processors and hardware in general, creating a & #34;containment barrier" that justifies the different price levels, putting a higher price on the most powerful processors.

Timeline

Predecessors (the roots of the x86 architecture)

• 1971 Datapoint 2200. Programmable computer terminal. Its set of instructions is the basis of the Intel processors from 8008 to 8085, which in turn are the ancestors of the x86 architecture
• 1972 Intel 8008
• 1974 Intel 8080
• 1977 Intel 8085

1. All microprocessors are not included

Chips of the x86 architecture

• 1978 and 1979 Intel 8086 and 8088. First microprocessors of the x86 architecture.
• 1980 Intel 8087. First numerical coprocessor of the x86 architecture, beginning of the x87 series.
• 1980 NEC V20 and V30. 8088 and 8086 processors, respectively, manufactured by NEC.
• 1982 Intel 80186 and 80188. Improvements of 8086 and 8088.
• 1982 Intel 80286. The protected mode appears, it has multitasking capacity.
• 1985 Intel 80386. First 32-bit x86 microprocessor.
• 1989 Intel 80486. It incorporates the numerical coprocessor into the integrated circuit itself.
• 1993 Intel Pentium. Better performance, superscalar architecture.
• 1995 Pentium Pro. Out-of-order execution and speculative execution
• 1996 Amd k5. Direct Intel Pentium Rival.
• 1997 Intel Pentium II. Improves code speed of 16 Bits, incorporates MMX
• 1998 AMD K6-2. Direct Intel Pentium II Competer, 3DNow Introduction!
• 1999 Intel Pentium III. Introduction of SSE instructions
• 2000 Intel Pentium 4. NetBurst. Improved SSE instructions
• 2005 Intel Pentium D. EM64T. Bit NX, Intel Viiv
• 2006 Intel Core 2. Introduction of Intel P8 microarchitecture. Reduced consumption, multiple cores, hardware virtualization support including x86-64 and SSSE3.

1. All microprocessors are not included.

Successors (x86-64 microprocessors)

• 2003 AMD Opteron. First 64-bit x86 processor, with the AMD64 set of instructions)

1. All microprocessors are not included

X86-64

With the eighth generation of x86-compatible processors, the x86-64, which use 64-bit architecture and bus, with the possibility of multiple cores, introduced by AMD and adopted by Intel, new variants and forms are introduced for the first time, as far as the denomination and classification of the processor is concerned, such as the commercial name or technology of the model, the manufacturing company, its serial number, the number of bits it can work at or the number of cores for which it is composed, for example: Intel Core 2 Duo E2180, or what is the same, i686 or Intel Pentium dual-core E2180, 64 bits and 1.6 to 2.0 GHz; or AMD Athlon 64 X2, that is, an AMD 64-bit, 2GHz dual-core Athlon X; all of them included under the common denominator x86-64, and compatible with previous subarchitectures of 32, 16 and 8 bits, of the family of x86 processors of Intel, and compatible.

Additional Data

Numeric Completion (Intel)

Intel Microprocessor D8086

The number 86 was used in the numeric ending of some Intel family microprocessors, for example D8086, to indicate that they used the x86 architecture or instruction set. They constituted from their birth a standard for computers of the IBM PC Compatible type.

Starting with the i486 microprocessor, non-numeric names were used, referring to the brand, logo, or codename under which they were released, and were often marketed followed by their frequency, in megahertz.

X86 processors

Intel

• 486SX
• 486DX
• 486DX2
• 486DX4
• Pentium
• Pentium II
• Pentium 4020
• Pentium III
• Pentium 4
• Pentium D
• Core 2 Quad
• Core 2 Duo
• Core i3
• Core i5
• Core i7
• Core i9
• [[lg k7 2018]

AMD

• K5
• K6
• K7 (Athlon, Athlon XP)
• Duron
• Sempron
• Ryzen

Cyrix

6x86

1. All x86 processors are not included.