Pentium III

From Wikipedia, the free encyclopedia

Pentium III Central processing unit
An Intel Pentium III Coppermine Processor.
Produced:	From early 1999 to early 2002
Manufacturer:	Intel
CPU Speeds:	450 MHz to 1.4 GHz
FSB Speeds:	100 MHz to 133 MHz
Process: (MOSFET channel length)	0.25 µm to 0.13 µm
Instruction Set:	x86
Microarchitecture:	P6
Sockets: Slot 1 Socket 370
Cores: Katmai Coppermine Coppermine-T Tualatin

Pentium III logo

Pentium III-M Logo

The Pentium III is an x86 (more specifically, an i686) architecture microprocessor by Intel, introduced on February 26, 1999. Initial versions were very similar to the earlier Pentium II, the most notable difference being the addition of SSE instructions and the introduction of a controversial serial number which was embedded in the chip during the manufacturing process. As with the Pentium II, there was also a low-end Celeron version and a high-end Xeon version. The Pentium III was eventually superseded by the Pentium 4. An improvement on the Pentium III design is the Pentium M.

Contents 1 Pentium III cores 1.1 Katmai 1.2 Coppermine 1.3 Coppermine-T 1.4 Tualatin 2 Pentium III's SSE Implementation 3 Core specifications 3.1 Katmai (0.25 µm) 3.2 Coppermine (0.18 µm) 3.3 Coppermine cD0-stepping or Coppermine-T (0.18 µm) 3.4 Tualatin (0.13 µm) 4 References 5 External links

[edit] Pentium III cores

[edit] Katmai

The original version, Katmai, was very similar to the Pentium II (using a 0.25 µm fabrication process), the only differences being the introduction of SSE, and an improved L1 cache controller (which was the cause of the minor performance improvements over the latter PIIs). It was first released at speeds of 450 and 500 MHz. Two more versions were released: 550 MHz on May 17, 1999 and 600 MHz on August 2, 1999. On September 27, 1999 Intel released the 533B and 600B running with 533/600 MHz but using a 133 MHz FSB, all others use a 100 MHz FSB.

The Katmai used the same slot based design as the Pentium II but with the newer SECC2 cartridge that allowed direct CPU core contact with the heatsink.

A notable stepping for enthusiasts was SL35D. This version of Katmai was officially rated for 450 MHz, but often contained cache chips for the 600 MHz model and thus usually was capable of running at 600 MHz.

[edit] Coppermine

The second version, Coppermine, had an integrated full-speed 256-bit 256 KiB L2 cache with lower latency, named Advanced Transfer Cache by Intel, which improved performance significantly over Katmai. Under competitive pressure from AMD’s Athlon processor, Intel also re-worked the chip internally, and finally fixed the well known instruction pipeline stalls. The result was a remarkable 30% increase in instruction processing performance per clock.

It was built on a 0.18 μm process. Pentium III Coppermines running at 500, 533, 550, 600, 650, 667, 700, and 733 MHz 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 1000 MHz (1 GHz). Both 100 MHz FSB and 133 MHz FSB models were made.

A 1.13 GHz 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 1.13 GHz speed without various tweaks to the processor's microcode, aggressive cooling, additional voltage (1.75 V vs. 1.65 V), and specifically validated platforms.^[1] 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 1.13 GHz CPU equalling a 1.0 GHz model. Tom's Hardware attributed this performance deficit to relaxed tuning of the CPU and motherboard to improve stability.^[2] Intel needed at least six months to resolve the problems and re-released 1.1 GHz and 1.13 GHz versions in 2001.

A common misconception is that a modified version of the Coppermine was developed for Microsoft's Xbox game console. The Xbox does not actually use a Pentium III processor per se. It technically runs a Mobile Celeron 733 (Coppermine-128) in a Micro-PGA2 package. Given the fact that the Mobile Celeron 733 has the same 8-way associative cache used in Pentium III chips, it isn't a stretch to just call the Xbox CPU a "Pentium III with half the cache." Still, that statement isn't entirely correct.

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

Later in Coppermine's life, Intel implemented a heatspreader to improve contact between the CPU and the heatsink. While the heatspreader itself didn't improve thermal conductivity, since it added another layer of metal and thermal paste between the CPU and the heatsink, it greatly assisted in holding the heatsink flat against the CPU. Earlier Coppermine CPUs with bare cores made for challenging heatsink mounting.^[3] If the heatsink was not flat against the core, 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.^[4]

[edit] Coppermine-T

This core was supposed to be 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 could work in older system boards. It existed in Intel's processor roadmap in 2000 but was cancelled on the way to production.

Intel did issue S-Spec production codes (e.g. SL5QK) for some late-model Coppermines that would work with low voltage system bus operation (GTL) at 1.25 V AGTL as well as normal 1.5 V AGTL+ signal levels, and would auto detect differential or single-ended clocking. These processors were probably intended for dual-processor motherboards. However core voltage was the same as other Coppermines.

Note: Some sources identified Coppermine cD0-stepping to be Coppermine-T. This is incorrect because cD0-stepping was merely a revision to the original Coppermine rather than a new core by itself. Intel was unlikely to have it placed in the roadmap as a new core codename. Stepping (version numbers) of processors could be compared to minor versions of software.

[edit] Tualatin

The third version, Tualatin, was really just a trial for Intel's new 0.13 µm process. As the Pentium 4 had a much bigger die size than the Pentium III, Intel would get more usable Pentium IIIs out of a wafer, and this would allow them to introduce the 0.13 µm Pentium 4 (Northwood) once the process was achieving optimal yields. Tualatin performed quite well, especially in variations which had 512 KiB L2 cache (called the Pentium III-S). The Pentium III-S variant was mainly intended for servers, especially those where power consumption mattered, i.e., thin blade servers.

Pentium III Tualatins were released during 2001 until early 2002 at speeds of 1.0, 1.13, 1.2, 1.26, 1.33 and 1.4 GHz. Overclockers discovered as well that 1.4-1.5 GHz with air-cooled temperatures was reaching the limits of the process.

Tualatins can usually be visually distinguished from Coppermine-based Pentium IIIs by the metal integrated heatspreader (IHS) fixed on top of the package, however the very last models of Coppermine Pentium IIIs also featured the integrated heat-spreader (IHS) - the heat-spreader is what distinguishes the FC-PGA2 package from the FC-PGA - both are for Socket 370 motherboards.^[5] Because the IHS slightly reduces heat transfer efficiency, some overclockers would remove it to allow direct die-to-heatsink contact. This was even more dangerous with the smaller 130 nm core than it had been with the 180 nm Coppermine, with a risk of cracking or chipping the core, and the difficulty to mate the CPU and heatsink flatly. However, it did potentially improve cooling which could allow higher overclocking results. ^[6] Like with Coppermine, as a measure of protection several companies manufactured aftermarket shims to aid in flat heatsink mounting.

The Tualatin core was named after the Tualatin Valley and Tualatin River in Oregon, where Intel has large manufacturing and design facilities.

[edit] Pentium III's SSE Implementation

Since Katmai was built in the same 0.25 µm process as Pentium II "Deschutes", it had to implement SSE using as little silicon as possible. To achieve this goal, Intel implemented the 128-bit architecture by double-cycling the existing 64-bit data paths and by merging the SIMD-FP multiplier unit with the x87 scalar FPU multiplier into a single unit. To utilize the existing 64-bit data paths, Katmai issues each SIMD-FP instruction as two μops. To compensate partially for implementing only half of SSE’s architectural width, Katmai implements the SIMD-FP adder as a separate unit on the second dispatch port. This organization allows one half of a SIMD multiply and one half of an independent SIMD add to be issued together bringing the peak throughput back to four FLOPS per cycle — at least for code with an even distribution of multiplies and adds.^[7]

The problem with Katmai’s method was that the hardware had implemented a different model of parallelism than was implied by the SSE architecture. This set up a code-scheduling dilemma: Should the code be scheduled for Katmai to maximize near-term performance or would it be better to schedule for the architecture in anticipation of a full implementation in a future processor? Intel solved this dilemma by simply not restoring the original conception. SSE programming optimal for Katmai worked generally well on Coppermine and Tualatin. SSE assembly optimized for Pentium III was not optimal for Pentium 4, however.

While the design of Pentium III's SSE was undoubtedly directly related to the need to maintain a strict die size for Katmai, Coppermine and Tualatin were manufactured on significantly smaller processes and could potentially have been equipped with a superior implementation if Intel had not built a 0.25 μm Pentium III. A more impressive implementation had to wait until the arrival of Pentium 4.

[edit] Core specifications

[edit] Katmai (0.25 µm)

• L1-Cache: 16 + 16 KiB (Data + Instructions)
• L2-Cache: 512 KiB, external chips on CPU module at 50% of CPU-speed
• MMX, SSE
• Slot 1
• Front side bus: 100, 133 MHz
• VCore: 2.0 V, (600 MHz: 2.05 V)
• First release: May 17, 1999
• Clockrate: 450-600 MHz
  • 100 MHz FSB: 450, 500, 550, 600 MHz
  • 133 MHz FSB: 533, 600 MHz (B-models)

[edit] Coppermine (0.18 µm)

• L1-Cache: 16 + 16 KiB (Data + Instructions)
• L2-Cache: 256 KiB, fullspeed
• MMX, SSE
• Slot 1, Socket 370 (FC-PGA)
• Front side bus: 100, 133 MHz
• VCore: 1.6V (cA2), 1.65 (cB0), 1.70 (cC0), 1.75 V (cD0, see below)
• First release: October 25, 1999
• Clockrate: 550 - 1133 MHz
  • 100 MHz FSB: 550, 600, 650, 700, 750, 800, 850, 900, 1000, 1100 MHz (E-Models)
  • 133 MHz FSB: 533, 600, 667, 733, 800, 866, 933, 1000, 1133 MHz (EB-Models)

[edit] Coppermine cD0-stepping or Coppermine-T (0.18 µm)

• L1-Cache: 16 + 16 KiB (Data + Instructions)
• L2-Cache: 256 KiB, fullspeed
• MMX, SSE
• Socket 370 (FC-PGA2)
• Front side bus: 133 MHz
• VCore: 1.75 V
• First release: June 2001
• Clockrate: 866, 933, 1000, 1133 MHz

[edit] Tualatin (0.13 µm)

• L1-Cache: 16 + 16 KiB (Data + Instructions)
• L2-Cache: 256 or 512 KiB, fullspeed
• MMX, SSE
• Socket 370 (FC-PGA2)
• Front side bus: 133 MHz
• VCore: 1.45, 1.475 V
• First release: 2001
• Clockrate: 1000 - 1400 MHz
  • Pentium III (256 KiB L2-Cache): 1000, 1133, 1200, 1333 MHz
  • Pentium III-S (512 KiB L2-Cache): 1133, 1266, 1400 MHz

[edit] References

1. ^ Pabst, Thomas. Intel Admits Problems With Pentium III 1.13 GHz: Production and Shipments Halted, Tom's Hardware, August 28, 2000.
2. ^ Pabst, Thomas. Latest Update On Intel's 1.13 GHz Pentium III, Tom's Hardware, August 28, 2000.
3. ^ Alpha FC-PAL35T & POP66T Cooler Review, The Tech Zone, April 12, 2000.
4. ^ Verbist, Tim. Copper Shims, Overclockers Online, December 3, 2000.
5. ^ Lal Shimpi, Anand. Intel Pentium III 1.2 GHz 0.13-micron Tualatin: The Celeron of the Future, Anandtech, July 30, 2001.
6. ^ Removing Your Integrated Heat Spreader, The Lunchbox, October 8, 2002.
7. ^ Diefendorff Keith (March 8, 1999). "Pentium III = Pentium II + SSE: Internet SSE Architecture Boosts Multimedia Performance". Microprocessor Report. Volume 13, Number 3.

[edit] External links

• Intel press release introducing Pentium III
• Intel press release introducing 0.18 µm Pentium IIIs
• Listing of various PII, PIII, and Celeron alphanumeric model designations
• Intel Pentium III technical specifications
• Comparison of 7th generation x86 CPU architectures
• Intel FAQ about the pentium III processor serial number

List of Intel microprocessors | List of Intel CPU slots and sockets

Intel processors 4004 | 4040 | 8008 | 8080 | 8085 | 8086 | 8088 | iAPX 432 | 80186 | 80188 | 80286 | 80386 | 80486 | i860 | i960 | Pentium | Pentium Pro | Pentium II | Celeron | Pentium III | XScale | Pentium 4 | Pentium M | Pentium D | Pentium Extreme Edition | Xeon | Core | Core 2 | Itanium | Itanium 2   (italics indicate non-x86 processors)