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| ====== Evolution of x86 Processors ====== | ====== Evolution of x86 Processors ====== |
| The evolution of x86 processors began with the Intel 8086 microprocessor introduced in 1978. It is worth noticing that the first IBM machines, the IBM PC and IBM XT, used the cheaper version 8088 with an 8-bit data bus. The 8088 was software compatible with 8086, but because of the use of an 8-bit external data bus, it allowed for a reduction in the cost of the whole computer. IBM later used the 8086 processors in personal computers named PS/2. Its successor, 80286, was used in the IBM AT personal computer, the extended version of the XT, and in the IBM PS/2 286 machine, which became the standard architecture for a variety of personal computers designed by many vendors. This started the history of personal computers based on the x86 family of processors. In this section, we will briefly describe the most important features and differences between models of x86 processors. | The evolution of x86 processors began with the Intel 8086 microprocessor introduced in 1978. It is worth noting that the first IBM machines, the IBM PC and IBM XT, used the cheaper 8088 processor with an 8-bit data bus. The 8088 was software compatible with the 8086, but due to the use of an 8-bit external data bus, it allowed for a reduction in the overall computer cost. IBM later used the 8086 processors in personal computers named PS/2. Its successor, 80286, was used in the IBM AT personal computer, the extended version of the XT, and in the IBM PS/2 286 machine, which became the standard architecture for a variety of personal computers designed by many vendors. This started the history of personal computers based on the x86 family of processors. In this section, we will briefly describe the most important features and differences between models of x86 processors. |
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| ===== 8086 ===== | ===== 8086 ===== |
| The 8086 is a 16-bit processor, which means it uses 16-bit registers. With the use of the segmentation operating in so-called real addressing mode and a 20-bit address bus, it can access up to 1MB of memory. The base clocking frequency of this model is 5 - 10 MHz. It implements a three-stage instruction pipeline (loosely pipelined) which allows the execution of up to three instructions at the same time. In parallel to the processor, Intel designed a whole set of supporting integrated circuits, which made it possible to build the computer. One of these chips is 8087 - a match coprocessor known now as the Floating Point Unit. | The 8086 is a 16-bit processor, which means it uses 16-bit registers. With the use of the segmentation operating in so-called real addressing mode and a 20-bit address bus, it can access up to 1MB of memory. The base clocking frequency of this model is 5 - 10 MHz. It implements a three-stage instruction pipeline (loosely pipelined), which allows the execution of up to three instructions at the same time. In parallel to the processor, Intel designed a whole set of supporting integrated circuits, which made it possible to build the computer. One of these chips is 8087 - a math coprocessor known now as the Floating Point Unit. |
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| ===== 80186 ===== | ===== 80186 ===== |
| This model includes additional hardware units and is designed to reduce the number of integrated circuits required to build the computer. Its clock generator operates at 6 - 20 MHz. 80186 implements a few additional instructions. It's considered the faster version of 8086. | This model includes additional hardware units and is designed to reduce the number of integrated circuits required to build the computer. Its clock generator operates at 6 - 20 MHz. 80186 implements a few additional instructions. It's considered the faster version of the 8086. |
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| ===== 80286 ===== | ===== 80286 ===== |
| Pentium III is very similar to Pentium II. The main enhancement is the addition of the Streaming SIMD Extensions (SSE) instruction set to accelerate SIMD floating point calculations. Due to the enhancement of the production process, it was also possible to increase the clocking frequency to the range of 400 MHz to 1.4 GHz. | Pentium III is very similar to Pentium II. The main enhancement is the addition of the Streaming SIMD Extensions (SSE) instruction set to accelerate SIMD floating point calculations. Due to the enhancement of the production process, it was also possible to increase the clocking frequency to the range of 400 MHz to 1.4 GHz. |
| ===== Pentium 4 ===== | ===== Pentium 4 ===== |
| Pentium 4 is the last 32-bit processor developed by Intel. Some late models also implement 64-bit enhancement. It is based on NetBurst architecture, which was developed as an improvement to P6 architecture. The important modification is a movement of the instruction cache from the input to the output of the instruction decoder. As a result, the cache, named trace cache, stores micro-operations instead of instructions. To increase the market impact, Intel decided to enlarge the number of pipeline stages, using the term "hyperpipelining" to describe the strategy of creating a very deep pipeline. A deep pipeline could lead to higher clock speeds, and Intel used it to build the marketing strategy. The Pentium 4's pipeline in the initial model is significantly deeper than that of its predecessors, having 20 stages. The Pentium 4 Prescott processor even has a pipeline of 31 stages. Operating frequency ranges from 1.3 GHz to 3.8 GHz. Intel also implemented the Hyper Threading technology in the Pentium 4 HT version to enable two virtual (logical) cores in one physical processor, which share the workload between them when possible. NetBurst architecture suffered from high heat emission, causing problems in heat dissipation and cooling. With Pentium 4, Intel returned to the single chip package for both the processor core and L2 cache. Pentium 4 extends the instruction set with SSE2 instructions, and Pentium 4 Prescott with SSE3. | Pentium 4 is the last 32-bit processor developed by Intel. Some late models also implement 64-bit enhancement. It is based on NetBurst architecture, which was developed as an improvement to P6 architecture. The important modification is a movement of the instruction cache from the input to the output of the instruction decoder. As a result, the cache, named trace cache, stores micro-operations instead of instructions. To increase the market impact, Intel decided to enlarge the number of pipeline stages, using the term "hyperpipelining" to describe the strategy of creating a very deep pipeline. A deep pipeline could lead to higher clock speeds, and Intel used it to build the marketing strategy. The Pentium 4's pipeline in the initial model is significantly deeper than that of its predecessors, having 20 stages. The Pentium 4 Prescott processor even has a pipeline of 31 stages. Operating frequency ranges from 1.3 GHz to 3.8 GHz. Intel also implemented the Hyper Threading technology in the Pentium 4 HT version to enable two virtual (logical) cores in one physical processor, which share the workload between them when possible. With Pentium 4, Intel returned to the single chip package for both the processor core and L2 cache. Pentium 4 extends the instruction set with SSE2 instructions, and Pentium 4 Prescott with SSE3. NetBurst architecture suffered from high heat emission, causing problems in heat dissipation and cooling. |
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| ===== AMD Opteron ===== | ===== AMD Opteron ===== |