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Figure 5-40 Pentium II

The Pentium II initially achieved the higher clock speeds by using high multiples of a 66-MHz external speed. During this time, however, AMD began to sell CPUs designed to run on 100-MHz motherboards. Although the final Pentium II models also ran on 100-MHz motherboards, Intel’s slow adoption of 100-MHz external-speed CPUs lost market share for Intel.

The SEC cartridge also created another problem: it was not free to copy. This prevented other CPU manufacturers from making CPUs that fit in the SEC’s special Slot 1 connection and forced AMD to create its own SEC packages that were incompatible with Intel’s. From the Pentium II to today, AMD and Intel CPUs are no longer interchangeable. We live in a world where AMD CPUs have motherboards designed for AMD, while Intel CPUs must have motherboards designed for Intel.

AMD K6 Series

From 1997 to 2000, AMD produced a series of processors called the K6 that matched—and in many people’s view, surpassed—the Pentium II, propelling AMD into serious competition with Intel (Figure 5-41). Four models were included in the K6 series: the K6, K6-2, K6-2+, and K6-III, each incorporating more advanced features than the previous model. The K6 processors incorporated a number of improvements, including a 64-KB L1 cache, extremely advanced pipelining, and support for motherboard speeds of up to 100 MHz (on later models). The K6-2 added AMD’s proprietary 3DNow! instruction set—a direct competitor to Intel’s MMX and a significant advancement in graphics-handling capabilities—and increased clock speeds. The K6-III included even more advancements in pipelining and added a 256-KB L2 cache, all on a standard Socket 7 PGA package.

Figure 5-41 AMD K6 (photo courtesy of AMD)

Pentium III

The Pentium III improved on the Pentium II by incorporating Streaming SIMD Extensions (SSE), Intel’s direct competitor to AMD’s 3DNow!; a number of internal processing/pipelining improvements; full support for 100-MHz and 133-MHz motherboard speeds; and a high-speed L2 cache. The Pentium III was first produced by using an SEC package (Figure 5-42), but improvements in die technology enabled Intel to produce PGA versions later, ending the short reign of the SEC-package CPUs.

Figure 5-42 Intel Pentium III

Practical Application

Processing and Wattage

To make smarter CPUs, Intel and AMD need to increase the number of microscopic transistor circuits in the CPU. The more circuits you add, the more power they need. CPUs measure their power use in units called watts, just like a common light bulb. Higher wattage also means higher heat, forcing modern CPUs to use powerful cooling methods. Good techs know how many watts a CPU needs, because this tells them how hot the CPU will get inside a PC. Known hot CPUs are often avoided for general-purpose PCs because these CPUs require more aggressive cooling.

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NOTE As you read the wattages for the various CPUs, imagine a light bulb with that wattage inside your system unit.

CPU makers really hate heat, but they still want to add more circuits; they constantly try to reduce the size of the circuits, because smaller circuits use less power. CPUs are made from silicon wafers. The electrical circuitry is etched onto the wafers with a process called photo lithography. Photo lithography is an amazingly complex process, but basically requires placing a thin layer of chemicals on the wafer. These chemicals are sensitive to ultraviolet light; if a part of this mask is exposed to UV light, it gets hard and resistant. If it isn’t exposed, it’s easy to remove. To make the circuitry, a mask of the circuits is placed over the wafer, and then the mask and wafer are exposed to UV light. The mask is removed and the wafer is washed in chemicals, leaving the circuits. If you want microscopic circuits, you need a mask with the pattern of the microscopic circuits. This is done though a photographic process. The old 8088 used a 3-micrometer (one millionth of a meter) process