Using PC as a telephone

Here is some info I found which may or may not make things clearer!! I am trying to compare the cyrix MII with theAMD K6 but I am finding it hard to find the info, seems the Cyrix may be faster at the same CPU speed. Very confusing.

Cyrix 6X86MX (MII)

Cyrix also has a high performance chip, placed between 5th and 6th generation. It was announced as M2, but introduced on May 30, 1997 the name became 6X86MX. Later it has been named MII again. There have always been some confusion about the identification of the Cyrix CPUs.

This 6X86MX chip is compatible with the Pentium MMX. This gives additional possibilities to buttemble PCs on ordinary Socket 7 motherboards.

The 6X86MX has 64 KB internal L1 cache, which is very impressive. Cyrix also utilize technologies which are not found in Pentium MMX. These chips are named to compare them with genuine Pentiums, although their internal clock speed is lower than corresponding Intel processors.

The 6x86MX is unique compared to the other 6. generation CPUs (Pentium II and Pro and K6) since it does not work upon a RISC kernel. 6x86MX executes the original CISC instructions as does the Pentium MMX.

The 6x86MX has plenty of internal registers:

CPU Number of 32 bit CPU registers Pentium MMX 8 6x86MX 32 Pentium Pro 40 K6 48

The 6x86MX has - as all processors from Cyrix - a problem concerning the FPU unit. However, using standard office applications, this is of no concern.

6X86MX Internal speed External speed PR166 150 MHz 60 MHz PR200 166 MHz 66 MHz PR233 188 MHz 75 MHz PR266 225 MHz 75 MHz PR300 233 MHz 66 MHz PR333 255 MHz 83 MHz PR350 300 MHz 100 MHz

The 6X86MX is quite a powerful chip - on the paper. However I do not think, that they always sell that well. There are problems with the supply of them, and also the system bus speed causes troubles. It is difficult to find motherboards that accepts these speeds. Hopefully this will change. They also lack good FPU and MMX performance, and they do not incorporate the 3DNow! technology.

It is evident that Cyrix intends to continue this line of processors, and this definitely is a positive trend. Intel gets compebreastion, and it keeps the well tested and inexpensive Socket 7 motherboards in the market.

The 6x86MX processor is produced by National-Cyrix as well as by IBM. The architecture is the same, but the chips are built at different plants.

On April 14, 1998 the Cyrix MII (M-two) version was launched. From what I understand it is exactly the same chip as the 6X86MX just running at higher clock frequencies.

The top models were in June 1998:

CPU Cyrix MII-300 IBM PR333 Technology 0.35 micron Semi 0.25 micron Possible clock speeds 3.5 X 66 MHz = 233 MHz 3.0 X 75 MHz = 225 MHz 4.0 X 66 MHz = 266 MHz 3,5 X 75 MHz = 263 MHz 3.0 X 83 MHz = 250 MHz

IBM uses a new technology for their PR333 chip. It is patented and called Flip-Chip. The die is soldered directly to the ceramic casing and this causes less induction. IBM is preparing for true 0.25 micron processing technology later this year, which will increase the external clock speed to 100 MHz.

Later we shall see the next Cyrix with IBM's copper technology, which will give a new performance boost. They expect PR350 and PR400 models before 1999 using the Super7 motherboard standards.

In 1999 we should have the new 3rd generation of the 6X86MX (code name Jalapeno). This CPU will be named MXi, and it will come in PR350 and PR400 flavors. The MXi is Socket 7 compatible, but it has an improved core running a 133 MHz system bus. It also should include new 3D instructions (3DNow!) and improved FPU..

Later Cyrix probably will build Pentium II compatible CPUs using the Slot 1 design, which they have license to produce.

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