Karbosguide.com - Module 3a3.

About modern CPUs


The contents:

  • Dual pipeline
  • Floating point unit - FPU
  • Graphic overview of the processors
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  • One is that the clock frequency increases, as we will see later - the faster, the better. But what can the CPU do in one clock tick. That is critical to its performance. For example, a 386 needed 6 clock ticks to add a number to a sub total. A job which the 486 manages in only two clock ticks, because of more effective instruction decoding.

    5th and 6th generation CPUs can execute more than one of those operations in one clock tick, since they contain more processing lines (pipelines), which work parallel:

    Please also read the section about MMX, about 3DNow!, and Katmai instructions.



    Floating point unit - FPU

    The first CPUs could only work with whole numbers. Therefore, it was necessary to add a mathematical co-processor (FPU), when better math power was needed. Later, this FPU was built into the CPU:

    CPU FPU
    8086 8087
    80286 80287
    80386 80387
    80486DX Built in
    80486SX None
    Pentium and thereafter Built in

    It is said that Intel's CPUs have by far the best FPU units. Processors from AMD and Cyrix definitely have a reputation for providing sub standard performance in this area. But, you may not utilize the FPU. That depends on the applications (user programs) you are using. Common office programs do not use the floating point operations, which the FPU can handle. However, 3D graphics programs like AutoCad do. And all 3D-games like Quake rely heavily on FPU perfomance! Read more of this subject here.

    Therefore, if you use your PC in advanced design applications, the FPU performance becomes significant. For some users, it is only of limited importance.


    Graphic overview of the processors

    There are CPUs of many brand names (IBM, Texas, Cyrix, AMD), and often they make models which overlap two generations. This can make it difficult to keep of track of CPUs. Here is an attempt to identify the various CPUs according to generation:


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    Learn more

    Click for Module 3c about the 5th generations CPUs (Pentiums etc.)

    Click for Module 3d about the clock frequencies

    Click for Module 3e about 6th generations CPUs (Pentium IIs etc.)

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