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The AMD K6-III Processor
The AMD K6-III Processor

The K6-III, code-named "Sharptooth", was an x86 microprocessor manufactured by AMD, which was the last and perhaps fastest of all Socket 7 desktop processors. See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated Socket 7 is a physical and electrical specification for an X86 -style CPU socket on a personal computer Motherboard. It was released on February 22, 1999, with 400- and 450-MHz models.

For an extremely short time after its release, the fastest available desktop processor from Intel was the Pentium II 450 MHz. However, the K6-III also competed against the Pentium III "Katmai" line, released just days later on February 26. "Katmai" CPUs reached speeds of 500 MHz, slightly faster than the K6-III 450 MHz. K6-III performance was significantly improved over the K6-2 due to the addition of an on-die L2 cache running at full clock speed. When equipped with a 1MB L3 cache (on the motherboard) the 400- and 450-MHz K6-IIIs could very nearly match the performance of the higher-priced Pentium III "Katmai" 450- and 500-MHz models, respectively.

The K6-III 450 MHz is sometimes touted, especially on the internet, as the first AMD processor to out-perform the top model offering from Intel. However, this is a difficult claim to support, for two principal reasons: Firstly, although the official launch of the K6-III preceded that of the faster Pentium III, the date of actual market availability may have come slightly later; second, processor performance across architectures is not perfectly scalar, and so although the Pentium II 450 MHz performed slower in certain areas, it was faster in others.

Contents

Architecture

The AMD K6-III architecture.
The AMD K6-III architecture.

In conception, the design is simple: it was a K6-2 with on-die L2 cache. The K6-2 was an X86 Microprocessor introduced by AMD on May 28 1998 and available in speeds ranging from 266 to 550 MHz. In execution, however, the design was not simple; with 21. 4 million transistors, it was a very large chip to manufacture with early 1999 technology, and the K6 core design did not scale well past 500 MHz. Nevertheless, the K6-III/400 sold well, and the AMD K6-III/450 was clearly the fastest x86 chip on the market on introduction, comfortably outperforming AMD K6-2's and Intel Pentium II's.

The K6-III implemented the x86 instruction set by translating x86 instructions into RISC86 operations internally and had separate multiplier and ALU for additional instructions to improve multimedia and 3D graphics performance. It also contained internal L1 cache with the full-speed L2 cache on the chip and could be supported by L3 cache on the ordinary motherboard.

Enhanced RISC86 microarchitecture

3DNow!

For more details on this topic, see 3DNow! . 3DNow! is the Trade name of a multimedia extension created by AMD for its processors starting with the K6-2 in 1998

A single instruction multiple data (SIMD) operations by a packed single-precision floating-point data format. In Computing, SIMD ( S ingle I nstruction M ultiple D ata is a technique employed to achieve data level parallelism as in a Vector It was an enhancement to the MMX instruction set, which contained 21 new instructions that support SIMD floating-point operations and includes SIMD integer operations, data prefetch, and faster MMX-to-floating-point switching. The K6-III+ had the "Enhanced 3DNow!"(Extended 3DNow! or 3DNow+) which added 5 new DSP instructions, but not the 19 new extended MMX instructions.

TriLevel Cache

The original K6-2 had a 64 KiB primary cache and a much larger amount of motherboard-mounted cache (usually 512 KiB or 1024 KiB but varying depending on the choice of main board). In computing binary prefixes are names or associated symbols that can precede a unit of measure (such as a Byte) to indicate multiplication by a power of two In contrast the competing Intel parts used 32 KiB of primary cache and either 128 KiB of full-speed secondary cache integrated into the CPU itself (Celeron) or 512 KiB of half-speed cache mounted on a processor daughter board (Pentium II, Pentium III). The Celeron brand is a range of X86 CPUs from Intel targeted at budget/value Personal computers €”with the motto "delivering great quality The Pentium II brand refers to Intel 's sixth-generation Microarchitecture (" Intel P6 " and x86 -compatible Microprocessors Pentium III variants Katmai The first Pentium III variant was the Katmai (Intel product code 80525

The K6-III, however, used both methods: it had 64 KiB primary cache, a massive 256 KiB on-chip, full-speed secondary cache (similar to the Celeron's but twice the size), and the variable size motherboard mounted cache on the Socket 7 or Super7 main board became L3 cache, so called "TriLevel Cache". Socket 7 is a physical and electrical specification for an X86 -style CPU socket on a personal computer Motherboard. The Super Socket 7, also referred to as Super 7, is an extension of the Socket 7 ZIF socket specification (up to 2 MB)

Market performance

Intel's Pentium-II replacement was not yet available but, as a stop-gap, Intel introduced a modestly revised version of the Pentium II and re-badged it as the "Pentium III". The Pentium II brand refers to Intel 's sixth-generation Microarchitecture (" Intel P6 " and x86 -compatible Microprocessors Pentium III variants Katmai The first Pentium III variant was the Katmai (Intel product code 80525 The base design was unchanged (the addition of SSE instructions was at that time of no performance significance) but Intel's new production process allowed clockspeed improvements, and it became difficult to determine which company's part was the faster. S treaming '''S'''IMD E xtensions ( SSE) is a SIMD (Single Instruction Multiple Data Instruction set extension to the X86 Most industry observers regarded the Intel part as superior for floating-point intensive tasks, but the K6-III as better for mainstream integer work.

Both firms were keen to establish a clear lead, and both experienced manufacturing problems with their higher-frequency parts. AMD chose not to sell a 500 MHz or faster K6-III after the rare 500 MHz K6-III had been immediately recalled; it was found to be drawing enough current to damage some motherboards. AMD preferred to concentrate on their soon-to-be-released Athlon instead. Athlon is the brand name applied to a series of different X86 processors designed and manufactured by AMD. Intel produced a 550 MHz Pentium-III with some success but their 600 MHz version had reliability issues and was soon recalled.

With the release of the Athlon, the K6-III became something of an orphan. Athlon is the brand name applied to a series of different X86 processors designed and manufactured by AMD. No longer a top-of-the-line part, it nevertheless required substantial manufacturing resources to produce: at 21. 4 million transistors, it was almost as expensive to make a K6-III as a 22-million-transistor Athlon, and the same area of silicon could make more than two of the 9. 3 million-transistor K6-2 parts. For a time, the K6-III was a low priority part for AMD—something to be made only when all orders for high-priced Athlons and cheap-to-produce K6-2s had been filled—and it became difficult to obtain in significant quantities.

The original K6-III went out of production when Intel released their "Coppermine" Pentium III (a much improved part that used internal, on-die cache like a Celeron or a K6-III) and, at the same time, switched to a new production process. Pentium III variants Katmai The first Pentium III variant was the Katmai (Intel product code 80525 The changeover was fraught with difficulties and Intel CPUs were in global short supply for 12 months or more. This, coupled with the outstanding performance of the Athlon, resulted in even many former Intel-only manufacturers ordering Athlon parts, and stretched AMD's manufacturing facilities to the limit. In consequence, AMD stopped making the K6-III in order to leave more room to manufacture Athlons (and K6-2s).

By the time the global CPU shortage was over, AMD had developed revised versions of the K6 family: the K6-2+ and the K6-III+. Essentially, both parts were K6-IIIs (the 2+ with a 128 KiB cache, the III+ with the full 256 KiB) made on a new 180nm production process. They were also the first processors to be available with the PowerNow! power saving technology. PowerNow! is speed throttling and power saving technology of AMD's processors used in Laptops The CPU 's Clock speed and VCore Essentially, the power savings were achieved with a combination of frequency (through adjusting multipliers) and voltage reduction.

Although targeted at notebook computers, both parts were also used by enthusiasts in desktop systems. AMD continued to devote their marketing resources to the Athlon and neither part became well-known outside the industry, but both had modest success and became firm favourites with the overclocking community. K6-III+ 450 MHz parts routinely overclocked to almost 600 MHz. Unfortunately, even with the 180 nm process, the K6 architecture's short 6-stage pipeline was stretched to the limit with regards to clock speed ramping. While the new "Coppermine" Pentium III was able to rise up to a final 1. 13 GHz clock speed, K6 III+ and 2+ never clocked higher than 570 MHz officially, with overclockers using air cooling achieving around 600 MHz at best.

Models

K6-III ("Sharptooth", K6-3D+, 250 nm)

K6-III-P (250 nm, mobile)

K6-III+ (180 nm, mobile)

External links

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