Features.

The Athlon XP builds upon the strengths that the AMD Athlon processor has had in that it possesses a three way ALU (Arithmetic Logic Unit) along with a fully superscalar, tri-pipelined x87 Floating Point Unit. The tri-pipelined x87 FPU of the K7 core has given the Athlon the best Floating Point performance since it’s introduction just over two years ago.

As AMD built upon the original K7 Athlon with the “Thunderbird” core of last year, the Athlon XP features 128 KB of level 1 cache, with 256 KB of exclusive level 2 cache. Essentially this uses the Level 2 cache essentially as an overflow from the processors Level 1 cache. For all intents and purposes we can view both the Level 1 and and Level 2 cache of the Athlon "Thunderbird" and Athlon XP as 384 Kb of unified cache as this is how it is used (in simple terms).

Where the Athlon XP’s “Palomino” core builds upon the Athlon “Thunderbird” is that it now features hardware data prefetch which enables it to fetch data from main memory and have it ready and waiting in cache ready for execution by the CPU. This feature is designed to help reduce the incidence cache stalls resulting from an data being present in cache when it is required by the CPU. If anything this has been a significant feature in recent CPU designs as it is incorporated into the Intel Pentium 4 and more recently the “Tulatin” 0.13 micron Pentium III and Celeron range.

The “Palomino” core of the Athlon XP also saw it’s Level 1 data TLB (Translation Look Aside) buffer increased from 32 to 40 entries. AMD have interestingly made both the Level 1 and Level 2 data TLB’s exclusive. Also both the Level 1 and Level 2 TLB’s can have data written to the speculatively.

The Athlon XP also features a revised core design which enables the Athlon XP to use up to 20% less power when compared to an equivalently clocked Athlon “Thunderbird” processor. This power reduction enables to the Athlon XP to run at lower temperatures when compared to an Athlon “Thunderbird” which consequently will enable the chip to be clocked to higher operating speeds, thus helping AMD to keep pace with the fast rising clock speeds of the Intel Pentium 4. Coupled to this feature is the presence of a thermal diode within the core of the Athlon XP. Whilst this has been a feature of Intel processors for some time, this is a very useful inclusion into the K7 derived core of the Athlon XP as it allows users (and the system) to monitor heat output.

Athlon XP - Intro.

Athlon XP - SSE.