Pentium III

Intel’s successor to the Pentium II, formerly codenamed Katmai, came to market in the spring of 1999. With the introduction of the MMX came the process called Single Instruction Multiple Data (SIMD). This enabled one instruction to perform the same function on several pieces of data simultaneously, improving the speed at which sets of data requiring the same operations could be processed. The new processor introduced 70 new Streaming SIMD Extensions – but doesn’t make any other architecture improvements.

50 of the new SIMD Extensions are intended to improve floating-point performance. In order to assist data manipulation there are eight new 128-bit floating-point registers. In combination, these enhancements can lead to up to four floating-point results being returned at each cycle of the processor. There are also 12 New Media instructions to complement the existing 57 integer MMX instructions by providing further support for multimedia data processing. The final 8 instructions are referred to by Intel as the New Cacheability instructions. They improve the efficiency of the CPU’s Level 1 cache and allow sophisticated software developers to boost the performance of their applications or games.

Other than this, the Pentium III makes no other architecture improvements. It still fits into Slot 1 motherboards, albeit with simplified packaging – the new SECC2 cartridge allows a heatsink to be mounted directly onto the processor card and uses less plastic in the casing. The CPU still has 32KB of Level 1 cache and will initially ship in 450MHz and 500MHz models with a frontside bus speed of 100MHz and 512KB of half-speed Level 2 cache, as in the Pentium II. This means that unless a user is running a 3D/games application that has been specifically written to take advantage of Streaming SIMD Extensions – or uses the 6.1 version or later of Microsoft’s DirectX API – they’re unlikely to see a significant performance benefit over a similarly clocked Pentium II.

October 1999 saw the launch of Pentium III processors, codenamed Coppermine, built using Intel’s advanced 0.18-micron process technology. This features structures that are smaller than 1/500th the thickness of a human hair – smaller than bacteria and smaller than the (human-) visible wavelength of light. The associated benefits include smaller die sizes and lower operating voltages, facilitating more compact and power-efficient system designs and making possible clock speeds of 1GHz and beyond. The desktop part was initially available in two forms, with either 100MHz or 133MHz FSBs at speeds ranging from 500MHz to 700MHz and 733MHz respectively. The part notation used differentiated 0.18-micron from 0.25-micron processors at the same frequency by the suffix E and versions with the 133MHz FSB by the suffix B.

Although the size of the Level 2 cache on the new Pentium IIIs was halved to 256KB, it was placed on the die itself to run at the same speed as the processor, rather than half the speed as before. The ability to operate at full-speed more than makes up for the missing 256KB. Intel refers to the enhanced cache as Advanced Transfer Cache. In real terms ATC means the cache is connected to the CPU via a 256-bit wide bus – four times wider than the 64-bit bus of a Katmai-based Pentium III. Overall system performance is further enhanced by Intel’s Advanced System Buffering technology, which increases the number of buffers between the processor and its system bus resulting in a consequent increase in information flow.

The announcement of the 850MHz and 866MHz Pentium IIIs in the spring of 2000 appeared to confirm Intel’s intention to rationalise CPU form factors across the board – signalled earlier by the announcement of the first 0.18-micron Celerons in a new FC-PGA (flip-chip pin grid array) packaging – with these versions being available in both SECC2 and FC-PGA packaging. The limited availability of FC-PGA compatible motherboards in the first half of 2000 created a market for the slot-to-socket adapter (SSA). This, however, resulted in something of a minefield for consumers, with some SSA/motherboard combinations causing CPUs to operate out of specification – thereby voiding the Intel processor limited warranty – and potentially damaging the processor and/or motherboard!

Soon after its launch on 31 July 2000, Intel faced the embarrassment of having to recall all of its shipped 1.13GHz Coppermine CPUs after it was discovered that the chip caused systems to hang when running certain applications. Many linked the problem with the increasing competition from rival chipmaker AMD – who had succeeded in beating Intel to the 1GHz barrier a few weeks earlier – believing that Intel may have been forced into introducing faster chips earlier than it had originally planned.

The new Tualatin Pentium III core was another example of the degree to which Intel had allowed its long-term technology plans to be derailed by short-term marketing considerations.