Codenamed "Tualatin" (a river in Oregon), Intel's latest Pentium III core builds largely on its predecessor - there is no 200MHz bus here, nor is there a 512KB L2 cache, at least in the case of the desktop version of Tualatin. In looking over the tech specs for Tualatin, one new feature stands out (besides the lower voltage, which we'll discuss shortly): the data prefetch logic.
Like Pentium 4 and AMD's Palomino core, Tualatin supports hardware prefetching. With this feature Tualatin watches access patterns in memory access, looking for common patterns. Based on this, the prefetch logic predicts which data will be needed next and fetches and places that data inside the processor's L2 cache before it's actually needed. This cuts down on the latency of the processor, and as we found in our Palomino Performance Preview, benefits tremendously from high bus speeds and high-speed memory such as RDRAM or DDR SDRAM. With its slower 133MHz bus offering only 1.06GB/sec of bandwidth, the data prefetch logic added to Tualatin is a nice feature to have, but would benefit considerably more if the Pentium III ran at a higher bus speed.
Like Coppermine, three versions of Tualatin will be available, one intended for use in servers, another in laptop computers, and the version we're reviewing today, which is intended for use in desktop systems. In terms of positioning, the focus for Tualatin is in the mobile segment, an area where the current Pentium 4 core is too large and consumes too much power to be an attractive solution. For desktops and servers, Intel Pentium 4 and Xeon will remain the flagship products. Tualatin is intended for use in desktops where low power or small form factor is desired, while server Tualatin chips are intended for use in ultra dense configurations.
While the server and laptop chips feature 512KB of L2 cache, desktop Tualatin chips only utilize 256KB. This practice of offering more onboard cache for the mobile and server versions is nothing new for Intel, previous chips in both segments have boasted this feature.
Making things somewhat confusing on the surface are the various clock speeds these new Pentium III chips support. For desktops, clock speeds of 1.13GHz and 1.2GHz are offered. The 0.13-micron version of the 1.13GHz part will be labeled Pentium III 1.13A, as a 0.18-micron Pentium III 1.13GHz is also available (and already shipping to Gateway). To help differentiate the server chips from the desktop parts, Intel uses an "S" to designate them. (The mobile chips are differentiated with an "M".)
In addition, server chips are available at higher clock speeds, while desktop Tualatin is limited to just 1.2GHz, 1.26GHz Pentium III-S chips are already available in Japan. Meanwhile, mobile chips are currently available at clock speeds up to 1.13GHz.
As a result of the 0.13-micron process, Tualatin chips require less voltage than older 0.18-micron Coppermine Pentium IIIs. In the case of Pentium III-S chips, the processor requires a voltage of 1.45V. Desktop Tualatin chips need a little more juice, 1.475V.