AMD Athlon: AMD's game changing CPU from 1999

On June 23, 1999, AMD announced its much anticipated Athlon CPU, the successor to its very successful K6. It launched less than two months later, on August 9, 1999. The Athlon proved to be the CPU that separated AMD from all of the other x86 CPU manufacturers who fell by the wayside. It was the first non-Intel x86 CPU that outperformed Intel’s fastest CPU at the time.

Cyrix, IDT, and Rise, oh my!

The AMD Athlon didn’t just look like a Pentium III, it outperformed it.

During the Pentium generation, an unprecedented number of x86 compatible CPU makers entered the market. Besides AMD and Cyrix, this generation also featured the IDT Winchip and the Rise MP6, which you may know as the core in the Vortex86 SoC. None of the competitors were as good all around as an Intel Pentium CPU, but they were all considerably less expensive, and most of them could do one or two things better than Intel did.

With the P6 generation, the Pentium Pro, Pentium II, and Pentium 3, Intel cut most of them off. They made enough changes to the processor bus and covered the new bus with enough patents that no third party could make a pin-compatible x86 CPU anymore. Anyone who dared to try to use Intel’s Socket 8, Slot 1, or Socket 370 was destined to repeat the history of the Chips & Technologies Super 386 or the UMC Green 486.

The lone exception was chipset maker VIA. VIA did it anyway, then sued Intel for violating one of its patents, forcing Intel into a patent-sharing agreement in order to gain rights to the P6 bus. VIA had acquired Cyrix and Centaur, the technology behind IDT’s Winchip CPU, and used Centaur’s technology to make a Socket 370 CPU in the 2000-2001 timeframe, but it was a budget chip. It was a Celeron competitor, not a Pentium III competitor.

AMD’s solution for carrying on with Athlon

AMD took a completely different route to compete with Intel. It got creative and licensed the EV6 Alpha processor bus from Digital Equipment Corporation. The Alpha was a high performance 64-bit RISC CPU architecture whose window of opportunity was rapidly closing in 1999, but it had a sophisticated, high speed bus that could reach the same types of speeds Intel was reaching with the P6. AMD was also able to hire displaced members of the DEC Alpha design team to supplement the design team they got from Nexgen.

But AMD found help from another unlikely source: Motorola. The two companies jointly developed a new manufacturing process that allowed both companies to reach higher clock speeds than they had before. The combination of these two things let AMD compete toe-to-toe with Intel. AMD had come a long way from the 5×86, a fifth-generation chip in name only that could only keep pace with Intel’s least expensive Pentiums, and the disappointing K5, which was efficient but couldn’t scale to high enough clock rates to compete.

The first Athlon CPUs did appropriate the Slot 1 connector that Intel used, and AMD simply flipped it around to keep end users from interchanging the two CPUs and damaging them in the process. Reusing a component that was already on the market allowed motherboard makers to save money by only having to keep a single part in stock and order in larger quantities.

And AMD released a chipset to give the Athlon multiprocessing capability too, helping cement it as a high-end contender.

AMD’s gamble

AMD’s theory was that hardware compatibility was less important than software compatibility. As long as they could convince motherboard manufacturers and chipset makers to produce quality motherboards and chipsets with comparable performance at a comparable price, they theorized they had a chance.

They were correct. AMD put together a winning combination that put them in an unfamiliar place: outperforming Intel at the high end of the market. While Intel had to recall its 1.13 GHz parts in January 2001 due to reliability issues, AMD had no problems scaling past 1 GHz.

In this generation, AMD managed to keep pace with or ahead of Intel in terms of clock speed from August 1999 into January 2002. This was a shift for AMD, who was used to starting out in the mid-range but quickly getting forced into the low end of the market. Intel didn’t take the performance crown away from AMD again until the Pentium 4.

Soon after Intel abandoned its Slot 1 connector in favor of a more traditional socket, AMD did the same thing, causing a divergence between AMD and Intel CPU sockets that persists to this day.

During this generation, AMD returned to profitability.

Going beyond the Athlon

The Athlon set the stage for AMD to turn the tables on Intel in the subsequent generation. The Athlon 64 extended the x86 architecture from 32 bits to 64 bits, and it outperformed the Pentium 4 generation. It was also more power efficient, so the Athlon 64 ended up seeing significant use in the business market, including the server market. Intel had to take the unprecedented step of cloning the AMD chip. But that’s a story for another time.