Gecko's CPU Library

Intel Pentium III (Coppermine) processors

Introduction: October 1999


The Pentium III brand refered to Intel's 32-bit x86 desktop and mobile microprocessors (with the sixth-generation Intel P6 microarchitecture) introduced on February 26, 1999. The initial Katmai Pentium III contained 9.5 million transistors. The brand's initial processors were very similar to the earlier CPUs branded Pentium II. The most notable difference was the addition of the SSE instruction set (to accelerate media processing and 3D graphics), and the introduction of a controversial serial number embedded in the chip during the manufacturing process.

Similarly to the Pentium II it superseded, the Pentium III was also accompanied by the Celeron brand for lower-end CPU versions, and the Xeon for high-end (server and workstation) derivatives. The Pentium III was eventually superseded by the Pentium 4, but its Tualatin core also served as the basis for the Pentium M CPUs, which used many ideas from the Intel P6 microarchitecture. Subsequently, it was the P-M microarchitecture of Pentium M branded CPUs, and not the NetBurst found in Pentium 4 processors, that formed the basis for Intel's energy-efficient Intel Core microarchitecture of CPUs branded Core 2, Pentium Dual-Core, Celeron (Core), and Xeon.

The Pentium III was the first Intel processor to break 1GFLOPS, with a theoretical performance of 2GFLOPS.

The Coppermine core

The second version, Coppermine, or 80526, had an integrated full-speed 256-bit 256KB L2 cache with lower latency, named Advanced Transfer Cache by Intel, which improved performance significantly over Katmai. Under competitive pressure from AMDs Athlon processor, Intel also re-worked the chip internally, and finally fixed the well known instruction pipeline stalls. The result was a remarkable 30% increased performance in some applications where these stalls happened.

It was built on a 0.18 m process. Pentium III Coppermines running at 500, 533, 550, 600, 650, 667, 700, and 733MHz were first released on October 25, 1999. From December 1999 to May 2000, Intel released Pentium IIIs running at speeds of 750, 800, 850, 866, 900, 933 and 1000MHz (1GHz). Both 100MHz FSB and 133MHz FSB models were made. An "E" was appended to the model name to indicate cores using the new 0.18 m fabrication process. An additional 'B' was later appended to designate 133MHz FSB models, resulting in an "EB" suffix.

A 1.13GHz version was released in mid-2000 but famously recalled after a collaboration between HardOCP and Tom's Hardware discovered various instabilities with the operation of the new CPU speed grade. The Coppermine core was unable to reliably reach the 1.13GHz speed without various tweaks to the processor's microcode, aggressive cooling, additional voltage (1.75V vs. 1.65V), and specifically validated platforms. Intel only officially supported the processor on its own VC820 i820-based motherboard, but even this motherboard displayed instability in the independent tests of the hardware review sites. In benchmarks that were stable, performance was shown to be sub-par, with the 1.13GHz CPU equalling a 1.0GHz model. Tom's Hardware attributed this performance deficit to relaxed tuning of the CPU and motherboard to improve stability. Intel needed at least six months to resolve the problems using a new cD0 stepping and re-released 1.1GHz and 1.13GHz versions in 2001.

Microsoft's Xbox game console used a variant of the Pentium III/Mobile Celeron family in a Micro-PGA2 form factor. The sSpec designator of the chips was SL5Sx, which made it most similar to the Mobile Celeron Coppermine-128 processor. It shared with the Coppermine-128 Celeron its 133MT/s front side bus, 128KB L2 cache, and 180 nm fabrication process.

Although the codename Coppermine made it sound as if the chip was fabricated with copper interconnects, Coppermine in fact used aluminum interconnects.

The Coppermine-T core

This revision was an intermediate step between Coppermine and Tualatin, with support for lower-voltage system logic present on the latter but core power within previously defined voltage specs of the former so it was able to work in older system boards. Intel used the latest Coppermines with the cD0-Stepping and modified them so that they worked with low voltage system bus operation (GTL) at 1.25V AGTL as well as normal 1.5V AGTL+ signal levels, and would auto detect differential or single-ended clocking. This modification made them compatible to the latest generation Socket-370 boards supporting FC-PGA2 packaged CPUs while maintaining combatility to the older FC-PGA boards. The Coppermine-T was also two way symmetrical multiprocessing capable but only in FC-PGA2 boards.

Intel also implemented an integrated heatspreader to improve contact between the die and the heatsink. The integrated heatspreader itself didn't improve thermal conductivity, since it added another layer of metal and thermal paste between the die and the heatsink, but it greatly assisted in holding the heatsink flat against the die. Earlier Coppermine CPUs without the integrated heatspreader made heatsink mounting challenging. If the heatsink was not flat against the die, heat transfer efficiency was crippled. Some heatsink makers also began using pads on their coolers, similar to what AMD did with the "Thunderbird" Athlon. The enthusiast community went so far as to create shims to assist in maintaining a flat interface.

Source: Wikipedia, the free encyclopedia.