The Intel Pentium 4 processor has come a long way since it was first introduced two years ago. At first, whole computing community was doubtful about the performance of Pentium 4. People were arguing that Pentium 4 is slower than AMD Athlon and Pentium III processors. But since then, the Pentium 4 underwent a series of changes especially, transition from 423 pin design to a smaller 478 pin design. Soon after this change, a new core, “Northwood” was introduced which replaced previous “Willamette” core and its die size was also reduced from .18µ to .13µ. This allowed Intel it to increase Pentium 4 cache from 256K to 512K. These all changes really helped Intel to boost performance of Pentium 4 processor, and currently it is that fastest processor available in the market.
Pentium 4 faced many difficulties in gaining market approval as the best processor available when compared to other processors such as Pentium III and AMD Athlon. The main reason for this was change in design and the migration from the P6 core of the Pentium III to the new faster NetBurst or P7 core of the current Pentium 4 processors.
Primary execution pipelines were increased in P7 core of Pentium 4 from 14 stages to 20 stages. The most noticeable effect of this modification to the normal observer and user is a rather big rise in execution latencies (i.e. Pentium 4 processor takes 20 clock cycles to complete an instruction as compared to 14 clock cycles in Pentium III.), which reduced the amount of output power per MHz when compared to older designs of Pentium III processor. As a rough rule of thumb, the initial 1.5GHz Pentium 4 was equivalent to 1 GHz Pentium III. Thus early Pentium 4 processors did not achieve the best of reputations in processor market. The 20 stage pipeline of the Pentium 4 processors brings the advantage of the ability to run at extremely high clock speeds, but it also brings a number of disadvantages.
The Rapid Execution Engine is one of the main architectural changes in the Pentium 4 processors. The Rapid Execution Engine sees the ALU (Arithmetic Logic Unit) of the Pentium 4 processor running at twice the frequency of the processor itself. This means in a 1.5 GHz Pentium 4, the integer calculations will be processed at a speed of 3 GHz.
In order to gain this extremely high speed Intel has had to “double pump” the Arithmetic Logic Unit, by allowing the logical gates of the processor to be triggered on the both falling and rising edge of the processor’s internal clock. This means that the Arithmetic Logic Unit is in fact being triggered on two times per clock cycle of processor as opposed to once in the P6 architecture.
When this was first announced by Intel, all people thought that the Pentium 4 processor would be equipped the fastest integer processing. It is now clear that Intel included this feature into the Pentium 4 processors to give it integer performance equivalent to previous P6 processors due to the introduction of the 20 stage pipeline. This feature is only likely to increase performance significantly when clock speeds rise above the 3 GHz point.
Other strong point of Pentium 4 processor is SSE2 instructions. SSE (Streaming SIM-D Extensions) was originally introduced with the Pentium III processor back in 1999 as a brand new method of performing Floating Point calculations efficiently. According to Intel:
“These instructions reduce the overall number of instructions required to execute a particular program task and as a result can contribute to an overall performance increase. They accelerate a broad range of applications, including video, speech, and image, photo processing, encryption, financial, engineering and scientific applications” (Web, 1).The 0.13 micron “Northwood” core of Pentium 4 processor (also known as Pentium 4 “A”) managed to achieve reputation of a chip to be considered for power hungry systems, and with due to a increase of cache from 256 KB to 512 KB (achieved through 0.13 micron core shrink) and continuously increasing clock speeds. Whilst the AMD Athlon processor, strong competitor to Pentium 4, is getting only 66 MHz increments, Intel is increasing speed of the Pentium 4 in 200 MHz gaps. Now Pentium 4 has gained the many advantage as compared to AMD Athlon, due to sheer clock speed. According to 3dvelocity.com:
“The new 0.13 micron process, which now also uses much more efficient copper interconnects as opposed to aluminum used for 0.18 micron dies, also means a great deal more headroom when it comes to clock speeds and speculation is that we'll see these cores clocked at 3.0GHz towards the end of this year or the beginning of 2003” (Web, 2)
After changing die size, Intel increased the Front Side Bus (FSB) speed of the Pentium 4 processor from 400 MHz to 533 MHz to release the new Pentium 4 processor, also known as Pentium 4 “B”. This increase further helped Intel to boost performance of Pentium 4 processor. The new Pentium 4 “B” version shares the same features, found in the Pentium 4 “A” version.
The Pentium 4 "B" version is great success of Intel’s NetBurst architecture. Pentium 4 is capable of running at extremely high clock speeds. It is currently available in various speeds such as: 1.7 GHz, 1.8 GHz, 1.9 GHz, 2.0 GHz, 2.26 GHz, 2.4 GHz, 2.53 GHz and 2.8 GHz. Intel is likely to introduce a new 3 GHz “Northwood” Pentium 4 in November, 2002. In fact many websites have already reported that 3 GHz speed can be achieved by overclocking easily.
Web, 1: The Intel Pentium 4 Processor: Product Overview
(October 27, 2002)
Web, 2: Intel Pentium 4 2.2A (Northwood)
(October 27, 2002)