Pentium III

Lore & Background

The Pentium III brand initially featured processors very similar to the earlier Pentium II, with the most notable differences being the addition of SSE and the controversial embedded serial number. The first variant, Katmai, was a further development of the Deschutes Pentium II, containing 9.5 million transistors plus 25 million for the 512 KB L2 cache, fabricated in a 250 nm process. It used the Slot 1 SECC2 cartridge and was released at speeds from 450 to 600 MHz, with later 'B' suffix models featuring a 133 MT/s FSB. A notable stepping, SL35D, was officially rated for 450 MHz but often contained cache chips for the 600 MHz model, allowing it to run at 600 MHz.

The second version, Coppermine, was released on October 25, 1999, with speeds from 500 MHz to 1 GHz. It introduced an on-chip L2 cache (Advanced Transfer Cache) of 256 KB operating at core clock speed, and was fabricated in a 180 nm process with 29 million transistors. Coppermine was available in FC-PGA or FC-PGA2 for Socket 370, or SECC2 for Slot 1. A 1.13 GHz version was released in mid-2000 but famously recalled after independent tests by HardOCP and Tom's Hardware discovered instabilities; Intel re-released 1.1 GHz and 1.13 GHz versions in 2001 with a new cD0 stepping. The Coppermine T revision was an intermediate step between Coppermine and Tualatin, supporting lower-voltage system logic while maintaining compatibility with older Socket 370 boards.

Reader's Guide

The Pentium III was eventually superseded by the Pentium 4, but its Tualatin core served as the basis for the Pentium M CPUs, which used many ideas from the P6 microarchitecture. It was the Pentium M microarchitecture, not the NetBurst found in Pentium 4 processors, that formed the basis for Intel's energy-efficient Core microarchitecture used in CPUs branded Core 2, Pentium Dual-Core, Celeron (Core), and Xeon. The Pentium III continued to be produced with new models introduced up until early 2003, and was discontinued in April 2004 for desktop units and May 2007 for mobile units. Microsoft's Xbox game console used a variant of the Pentium III/Mobile Celeron family in a Micro-PGA2 form factor, sharing the 128 KB L2 cache and 180 nm process with the Mobile Celeron Coppermine-128 but keeping the 8-way cache associativity from the Pentium III. The Coppermine core's interconnects were aluminium despite its codename suggesting copper.

Did You Know?

• The Pentium III introduced a controversial serial number embedded in the chip during manufacturing, absent on Tualatin and later Intel processors.
• The Katmai variant contained 9.5 million transistors, not including the 512 KB L2 cache which added 25 million transistors.
• A 1.13 GHz Coppermine version was recalled in mid-2000 after instability was discovered by HardOCP and Tom's Hardware.
• Microsoft's Xbox used a Pentium III/Mobile Celeron variant with 128 KB L2 cache and 180 nm process.