Tweak3D.net - AMD's Athlon: How It Works

Posted: April 12, 2000
Written by: Tuan "Solace" Nguyen

Introduction

Ever since the days of the i80486, Intel has held a tight grip on the processor market with the strength of a typhoon, blowing away any competitor that dared step in its path; and, for good reason too - Intel was far bigger, far better, and far faster.

Then came the Pentium, the Pentium Pro, the Pentium MMX, the Pentium II, the Pentium II Celeron, and the Pentium III. It looked as though Intel's biggest competitor - AMD, was about to be crushed by the hands of the processor giant.

AMD held records of below average performing processors and delayed product deliveries. It could have been bad luck for AMD or they just weren't cut-out to compete against Intel.

Then one day AMD releases the K6-III processor to compete against the Pentium II series. Surprising the computing audience, the K6-III smashed down the Pentium with speed left to spare. Unfortunately, this wasn't a total win for AMD. Carrying the legacy of the K6 series processors, the K6-III was flawed with extremely poor floating point calculation performance. Almost half that of Intel's chips. This didn't do well with the gaming and graphics community as that sort of thing requires very high performing floating point calculations.

But little did Intel know, AMD was preparing to launch a processor the likes of which Intel has never seen.

1999 arrives and AMD announces to the world the most powerful x86 processor to date:

The AMD (Advanced Micro Devices) Athlon Processor.

The Athlon processor is built on an entirely new architecture. Not one based on Intel's design, but designed from the ground up. The Athlon processor is geared to crash Intel's party and shove it off the thrown. And rest assured - it can.

It’s April, 2000 and AMD has just reported sales in excess of $1 billion and rising. You’ve probably heard of the processor for sometime and know that virtually everyone who talks about it, talks about how the Athlon is AMD’s weapon to de-thrown Intel as the king of processors. We all know it’s fast, but what makes it such a workhorse? Why, MHz-for-MHz does it rise about a Pentium III? Here’s how…

Here are the specs for AMD's greatest creation:

- Bus Interface: Alpha EV6 200MHz ~ 400MHz
- Speeds (MHz): 500 to 1Ghz in 50MHz bins
- Number of transistors: 22 million @ 0.25u 6-layer metal
- Clock Multiplier: 5x, to 10x in .5x
- L1 Cache: 128KB two-way set associative
- L2 Cache: 512KB ~ 8MB Internal
- L2 Speed: 1/2, 2/5 and 1/3 Core speed
- Memory bus speed: 100MHz to 133MHz*
- Memory bus bandwidth: 800MB/sec
- Maximum physical memory addressability: 64GB
- Maximum x86 instructions decoded/cycle: 3
- Number of MMX units: 2
- SIMD units: MMX, 3Dnow!, Enhanced 3DNow! DSP
- Current die size: 184 mm2
- Scalability: 1 (support for more in year 2000)
- Physical Interface: 242-contact Slot-A

*133MHz FSB using VIA Technologies' KX133 corelogic.

Housing 22 million transistors, the Athlon is the largest x86 processor to date. Here's a single transistor at actual size. Of course, the ones inside the Athlon a much smaller - 0.25 and 0.18 microns - smaller than some bacteria.

The sheer number of transistors that the Athlon packs doesn't denote extreme performance however. It depends how well those little switches are being used! So, we'll show you.

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