Hardware Museum

Over 20 years of PC history


CPU History Tour (1999 - 2001)

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Second part of the CPU benchmark project. This time starting with early Pentium III and Athlon Classic and following the CPU development up to the end of 2001 when Pentium III-S, Pentium 4 and Athlon XP were the top.

Athlon, Athlon Thunderbird

AMD Athlon processors competed very well with the first Penium III (Katmai) and in some areas provided even better perfomance. With 180 nm process available, the gigahertz war began. While Intel utilized 256 kB on-die L2 cache running at full speed, AMD sticked with older concept of external L2 cache located on the SECC module. The K7 architecture had no problem with high frequency, so AMD could raise the clock to 1 GHz within few months. The 1 GHz Athlon was introducesd on March 6th, 2000 - two days before Pentium III 1 GHz. Cache design was the major problem. All Athlons up to 700 MHz used cache running at half frequency (350 MHz top). AMD couldn't scale the cache clock any higher and therefore had to adjust the divider to 2/5 (for Athlon 750 - 850) or even 1/3 (for Athlon 900 - 1000). Because of this limitation faster Athlon variants fell behind Pentium III of the same clock. The slow cache turned out to be significant bottleneck.

AMD Athlon with AOpen AK72

Of course AMD was well aware of this problem and had successor of K75 ready in short time. Thunderbird, much like PIII Coppermine, integrated the L2 cache to the CPU silicon and reduced capacity to 256 kB at the same time. The cache organization was also changed - the original Athlon used inclusive cache concept, while Thunderbird utilized exclusive cache. Besides cache, AMD also developed new Socket A (sometimes called Socket 462). Most Thunderbirds were sold in Socket A package. But older Slot A variant also existed.

New Athlons became available in June 2000. There were 9 variants starting at 600 MHz and up to 1 GHz. Till the end of the year AMD managed to push operating frequency to 1.2 GHz. Some versions used faster 266 MHz FSB - this improved performance in some applications. There was still some room for improvement left - in 2001 Athlon 1266, 1300, 1333 and 1400 were introduced.

All changes had positive impact on performance compared to older Slot A athlons. New Socket A chipsets (especially VIA KT133A and KT266A with DDR memory) also greatly contributed to Athlon Thunderbird success.

Slot A, Socket 462 chipsets
AMD-750noSDR200 MHz768 MB2.21× / 2×
VIA KX133noSDR200 MHz1536 MB2.2
VIA KT133AnoSDR266 MHz1536 MB2.2
VIA KT266AnoSDR, DDR266 MHz4096 MB2.2
AMD-760MPXyesDDR266 MHz4096 MB2.2
SiS 745noDDR266 MHz3072 MB2.2

Athlon XP

Although the raw performance of Athlon Thunderbird was very competitive, in some applications Pentium III and 4 exjoyed significant lead because of SSE and SSE2 instruction set. Athlon supported MMX, 3DNow! and subset of SSE called MMX Extended (also known as MMX2). Full SSE support however was missing. And that was the most significant feature of Athlon XP (codename Palomino). Other than SSE addition, AMD also performned some minor performance optimalizations and reduction of power consumption. Manufacturing process remained at 180 nm, but thanks to the improvements clock raised to 1733 MHz for the fastest Palomino 2100+.

AMD Athlon Thunderbird and Athlon XP Palomino

The difference between Thunderbird and Athlon XP was really easy to see. AMD stopped using ceramic packages - all AXP utilized OPGA package. Because of internal structure changes even the outer shape was different. While Thunderbird was rectangular shape, Palomino was perfect square. Interesting fact is the transistor count didn't really change (37 to 37.5 million) and die size increased by 8 mm2 to 128 mm2 total.

Athlon XP was significantly faster than Pentium 4 running at similar clockspeed. P4 however was capable of much higher frequency. Therefore AMD reintroduced performance rating in order to better match Pentium 4 to AXP marking. Officially the XP rating was related to Athlon Thunderbird. The Palomino core could be found on 7 variants of Athlon XP. The first four - 1500+ (1333 MHz) to 1800+ (1533 MHz) were announced in October 2001. One month later AXP 1900+ (1600 MHz) was launched and during Q1 2002, Palomino 2000+ (1667 MHz) and 2100+ (1733 MHz) were ready.

Other than desktop Athlon XP and mobile Athlon 4, also Athlon MP processors were based on the Palomino core. These were intended for workstation and server usage. Athlon MP the first ever AMD CPU to support 2-way SMP. Unofficially Athlon Thunderbird also supported SMP, but this solution was problematic and in some cases unstable. At the time Athlon MP was competitor to much more expensive Xeon processors. Some dual-Socket motherboards could also run pair of Athlon XP or even Duron (with easy modification). Performance of such system was great considering the low price.

Duron – Spitfire, Morgan

The K7 architecture and especially Athlon processors were focused on hiend. At first the mainstream and lowend class were left to previous generation - K6-2 processors. The price was very low, but performance lacked behind Celerons and also Socket 7 platform was obsolete. Slot A didn't suit well cheaper CPUs, so Durons had to wait till introduction of Athlon Thunderbird (summer 2000) and the new Socket 462.

The first generation of Duron (codename Spitfire) was derived from Athlon Thunderbird. The only difference was reduced L2 cache to 64 kB. The main goal of AMD was to cut the manufacturing cost to minimum, because of that Duron used different die that only had 64 kB of L2. They didn't use partially disabled Thunderbird cores. This strategy allowed die size reduction by 20 mm2 compared to the Athlon. Duron Spitfire operated at 600 to 900 MHz, with 50 MHz steps. FSB always ran at 200 MHz (DDR).

In the second half of 2001 it was time for Duron lineup refresh. Along with Athlon XP, AMD also introduced Durons based on the new technology. Duron Morgan was very similar to Palomino, but with reduced L2 cache to 64 kB - just like the last generation. The top model reached 1.3 GHz with FSB still at 200 MHz.

At the time Duron processors were very popular. They offered good performance for a low price. The second generation (Morgan based) even unofficially supported SMP and thus allowed cheap and powerful dual CPU computers.

AMD Athlon Thunderbird with KT133A board
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