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Intel Pentium III

256 Kb integrated level 2 cache running at clock speed.

One of the main features that is appearing with the "Coppermine" is the introduction of 256 Kb, full speed level 2 cache on the processor die itself. This can be contrasted to the 512 Kb, half speed level 2 cache which was mounted on the processor module (i.e not on chip) that was the norm with the "Katmai" Pentium III and the Pentium II before that. The 256 Kb integrated cache arrangement brings with it a number of advantages.

The main advantage that this brings is that "Coppermine" is a one chip solution, as it integrates the CPU, level 2 cache and the cache controller onto one piece of silicon. This reduces manufacturing costs considerable as there is no longer the need for separate CPU, cache and cache controller chips as is found on "Katmai" Pentium III's and also on AMD's Athlon. The new one-chip arrangement allows Intel to manufacture the "Coppermine" in the cheaper socketed format, as is found with the new PIII 500(E) and 550(E) processors. For the time being, the rest of the "Coppermine" range will be manufactured in a Slot 1 package. Intel does intend to migrate the "Coppermine" based Pentium III range to a Socketed format with based upon the i820 chipset (when it appears).

The integrated 256 Kb level 2 cache arrangement does allow the "Coppermine" to make a significant number of performance gains over the older "Katmai" design with it's bigger but slower cache arrangement. The speed of the cache is what is makes the difference here and the performance boost in integer operations (which often need a fast cache) is noticable. As well as the operating speed of the cache it has been enhanced by features such as a 256 bit wide data path and lower latency.

The 256 bit wide data path is 4 times wider than the 64 bit data path on "Katmai" Pentium III processors, resulting in a far higher rate of data transfer. This is coupled to a reduced cache latency, which in turn reduces the performance penalty of any Level 1 cache misses.

The Level 1 cache of the "Coppermine" remains unchanged at 32 Kb, but other enhancements to the P6 core allow Intel to make a number of improvements over the older "Katmai" Pentium III.

Advanced System Buffering.

On its own, the improved cache sub-system on the "Coppermine" would be of only limited value if no modifications were made to the actual processor itself. In order to take advantage of the vastly improved data flow from the Level 2 cache, Intel had had to increase the size of the buffers within the CPU. Here we see an increase in the number of buffers which allow more data to transfered from the Front Side Bus.

This feature is especially useful in conjunction with the 133 MHz Front Side Bus.

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133 MHz bus.

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