KarbosGuide.com. Module 3e.07a

The Pentium III - Katmai and SSE

The contents:

  • Katmai New Instructions (KNI)
  • Two new features
  • The ID number – panic, panic
  • SSE
  • New registers
  • Program support with DirectX 6.1
  • My conclusion
  • Next page
  • Previous page

  • The first P6 CPU from Intel was the Pentium Pro. Later we got the Pentium II in various flavours (including the popular Celeron). In 1999 the time came for the Pentium III.

    Katmai New Instructions (KNI)

    In March 1999 Intel introduced the new enhanced MMX2 set of graphics instructions (70 of them). These are called Katmai New Instructions (KNI) or SSE. They are intended to speed up 3D gaming performance - just like AMD's 3DNow! technology. Katmai includes "double precision floating point single instruction multiple data" (or DPFS SIMD for short) running in eight 128 bit registers.

    Katmai New Instructions (KNI) was introduced with the 450 and 500 MHz Pentium III. It was processors very similar to the old Pentium IIs, using Slot 1.

    The only new feature was the implementation of Katmai and SSE, which I shall try to describe in this page.

    Two new features

    In fact the Pentium III contained two rather different news items, one small and one somewhat bigger. Intel's new top processor is a Pentium II in principle. It is mounted in a BX based motherboard with Slot 1. This processor has some built-in features:

  • A rather problematic ID numbering.
  • New registers and 70 new instructions.

    Finally the clock speed was raised to 500 MHz with room for further increases. Pentium III Xeon (code name Tanner) was introduced March 17th, 1999. It was a Xeon chip updated with all the new features from Pentium III. To utilize it Intel has the 840 chipset.

    The ID number – panic, panic

    The ID number PSN (Processor Serial Number), which is unique for each CPU, has caused lots of security discussions. It is a 96 bit value that is electronically programmed into each chip. Actually it was meant as a very sensible initiative, which could make electronic trade and encrypting on the Internet more secure and effective.

    The advocates see the ID number as "the permanent cookie."However it turns out that hackers and crackers can easily access the number, which makes the security dubious. At the same time the system is proposing a global registry of Internet users, which can easily be misused for marketing, etc. That will be invasion of privacy, if you no longer can remain anonymous on the Internet.

    SSE etc.

    The somewhat bigger news item is a real change in the basic processor architecture. It is actually the first change since 1985, where the x86 architecture was expanded from 16 to 32 bit (compared with the 386 processor).

  • New 128 bit registers, which each can handle four floating-point numbers.

  • Streaming SIMD Extensions (SSE). 50 new instructions, which enable simultaneous, advanced calculations of more floating-point numbers with a single instruction.

  • New Media Instructions. 12 new instructions in this category, which include other instructions for floating-point decimal calculations besides instructions that are designed for coding and decoding of MPEG-2 video streams "on the fly."

  • Streaming Memory. Here are 8 new instructions, which improve the interaction between L2-cache and RAM. With optimum utilization of the instructions, it could result in a 20% improvement of the bandwidth on the system bus. These instructions require newly-compiled programs, so it may be some time before we see the effect of this.

    The combined new instructions are called KNI (Katmai New Instructions) or SSE. The Pentium III construction is an attempt at improving the FPU performance in the processor. The registers are used by the new Katmai instructions.

    New registers

    The new 128 bit registers can potentially speed up 3D-graphics and multimedia handling, since the registers can contain four of the important 32 bit floating-point decimal numbers. Since the registers are a new physical creation within the CPU, they require support in the operating system to utilize them. Such support is expected soon in Windows 98.

    Program support with DirectX

    Microsoft's DirectX program layer is optimized relative to Katmai. With that, a large number of existing programs should benefit from the additional power of Pentium III (when DirectX 6.1 or better is installed). However the drivers for sound and graphics cards need to be re-written, to enable utilization of the new DirectX edition. Games that are not based on DirectX need to be re-written or expanded with patches, which utilize Katmai. Finally, a patch has been announced for the operating system itself, Windows 98, which should support the new instructions. Whether it will support all or only part of them is yet unknown.


    In April 1999 came reports of heat problems with the 550 MHz version. It should be very very hot, so big fans are the issue here...

    July 31, 1999. The 600 MHz version was launched. Later the "Coppermine" version was introduced with Socket370, as you will see in the following page.

    A provisional evaluation

    It is difficult to evaluate the significance of Pentium III’s new registers and instructions. However, it seems that most programs, drivers, etc. are being tuned for the new instructions. Then there is no doubt that the multimedia capabilities have received a great boost. There could be a doubling of their performance. So far Adobe have included support for SSE in version 5.5 of Photoshop. This works very well, some very time-consuming processes has been shortened with approx. 40%.

    The question is, if AMD will be forced to work in SSE etc. in their top processors or if they will continue the development of 3DNow!. In that case we'll have two systems to work with. Perhaps this is not a problem.

    Please read about Cumine and other new chips following Pentium III in the next module.

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    Learn more

    Read about chip sets on the motherboard in module 2d

    Read more about RAM in module 2e

    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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