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Module 3c4. The 5th generations CPUs - continued


  • Chip production
  • Moore's Law
  • Various notes about CPUs
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  • Chip production

    It takes a long time to manufacture a CPU. 5 to 50 million transistors must be placed on a tiny silicon wafer. Actually, it required 90 workdays 24 hours round-the-clock to produce a Pentium CPU.

    CPUs are manufactured in large wafers containing maybe 140 to 150 CPUs. Usually 110 to 120 of these perform perfectly. The rest are discarded. The wafers are burned, etched, and treated in hour long processes - layer by layer. In the CPU there are up to 20 layers of silicon wafers with millions of micro transistors.


    Process technology

    The CPUs are processed using CMOS technology with smaller and smaller "wires". The result is smaller "dies" (the little area inside the chip holding all the transistors) with more and more transistors. The power consumption goes down, and the clock frequency goes up.

    CPU Process technology Number of transistors die size
    486
    1.0 micron
    1,200,000
    79 mm2
    Intel Pentium
    0.5 micron
    3,100,000
    161 mm2
    Cyrix 6X86
    0.5 micron
    3,100,000
    392 mm2
    Intel Pentium MMX
    0.35 micron
    5,500,000
    128 mm2
    AMD K6
    0.25 micron
    8,000,000
    68 mm2
    Intel Pentium II
    0.35 micron
    0.25 micron
    7,500,000
    131 mm2
    Intel Celeron
    0.25 micron
    7,500,000
    131 mm2
    155 mm2
    Cyrix MII
    0.25 micron
    6,500,000
    119 mm2
    IDT
    WinChip 2 3D
    0.25 micron
    6,000,000
    88 mm2
    AMD K6-2
    0.25 micron
    9,300,000
    81 mm2
    AMD K6-3
    0.25 micron
    ?
    118 mm2
    AMD ATHLON
    0.25 micron
    22,000,000
    184 mm2
    Intel Pentium III CuMine
    0.18 micron
    28,000,000
    106 mm2
    AMD ATHLON "Thunderbird"
    0.18 micron
    37,000,000
    (22 mil. + 15 mil.)
    117 mm2
    Intel Pentium 4
    0.18 micron
    42,000,000
    217 mm2
    Intel Pentium 4 Northwood
    0.13 micron
    42,000,000
    116 mm2
    Athlon T
    0.13 micron
    37,000,000
    80 mm2

    Here you see the Intel process generations:

    Process generation Year Gate length
    P648
    1989
    1.0 micron
    P650
    1991
    0.8 micron
    P852
    1993
    0.5 micron
    P854
    1995
    0.35 micron
    P856
    1997
    0.25 micron
    P858
    2000
    0.18/0.13 micron

    Moore's Law

    The CPUs have doubled their calculating capacity every 18 months. This is called "Moore's Law" and was predicted in 1965 by Gordon Moore. He was right for more than 30 years. The latest CPUs use internal wiring only 0.25 microns wide (1/400 of a human hair). But if Moore's Law has to be valid into the next century, more transistors have to be squeezed onto silicon layers.

    IBM succeeded as the first in making copper conductors instead of aluminum. Copper is cheaper and faster, but the problem was to isolate it from the silicon. The problem has been solved with a new type of coating, and now chips can be designed with 0.13 micron technology. The technology is expected later to work with just 0.05 micron wiring!

    Texas Instruments announced on August 27th 1998 that they expect 0.07 micron CMOS processing in the year 2001.

    AMD was the first company to mass-produce copper-wired CPU's. This happened in their fab 30 in Dresden, April 2000.


    Chip errors

    The following miscalculations occur in 386, 486, and Pentium, when running Excel, Works, or Pascal, with the numbers 49 and 187:

    All CPUs have faulty instructions. Recently flaws have been discovered within the Pentium II and Cyrix 6x86MX.


    The Pentium scandal

    Pentium was hit by a scandal in late 1994, when an error in the mathematical co-processor (FPU) became publicly known. It simply miscalculated at a given division. Intel knew of the error from early that summer but more or less kept it secret.

    Intel insisted that the error would occur extremely rarely. Compaq immediately modified their production to disable the FPU. Shortly thereafter, IBM announced that they would stop the production of Pentium based PCs. IBM had calculated that the error would occur every 24 days. At the time, IBM was working to extricate themselves from the Intel CPU monopoly. They were moving towards Power PC, Cyrix, and NexGen based PCs. Thus the scandal played right into their hands. You see the error here, where A3 should be equal to A1:

    Intel underestimated the significance of the miscalculations, certainly regarding users employing complex mathematical calculations. IBM over dramatized the error for political reasons. This all happened in December 1994, while Intel was running their big TV campaign for Pentium.

    That gave birth to a number of jokes: How many Pentium programmers are needed to screw in a bulb? (answer: 1.9990427). Why is Pentium not named 586? Because it would have to be called 585.999983405! In a different vein: How many Apple employees does it require to change a bulb? 7! One to hold the bulb and 6 to design T-shirts. And: how many IBM employees does it require to change a bulb? None! IBM simply announces a new feature called "black bulb."


    Intel Owner's Club site

    This site is good if you are interested in the CPUs. Find the Intel Owner's Club, which is a free, easy way for members to:

  • get the scoop on the latest Intel technologies
  • get info on hot new software and technologies
  • interact with Intel & technology experts
  • download free software and games
  • enter contests.

    My membership has helped me to learn how to use the Intel web site, which holds a lot of information. Only Intel's servers can be terrible slow, so you easily get tired from them.


  • PC Architecture. A book by Michael B. Karbo - about CPUs
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    Learn more

    Or continue with the 6th generation CPUs. Click for Module 3e.

    Read module 5a about expansion cards, where we evaluate the I/O buses from the port side.

    Read module 5b about AGP and module 5c about Firewire.

    Read module 7a about monitors, and 7b on graphics card.

    Read module 7c about sound cards, and 7d on digital sound and music.

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