The Spiciest Piece of Silicon - Pentium 4
History has shown that processors from Intel have long been a popular choice amongst the computer geeks around the world. Right from the Intel's first 4004 processor, they have made an indelible mark in the industry. The latest offspring from the Intel labs, after 5 years of research is the Pentium 4, which was launched around a year ago. Unlike its predecessors, which were mere improvements or limited editions of the earlier processors, this one is totally redesigned from scratch.
Breaking all old traditions, this processor has done away with the familiar P6 architecture, which was seen right from the Pentium Pros till the Coppermines of today and instead has brought along the new Netburst architecture with a 20-stage instruction pipeline. Even the core of the processor and its microarchitecture have undergone a complete alteration. Featuring a 423 pin interface and carrying a humongous 48 million transistors the slowest this thing can get is 1.3Ghz (1300 MHz) and the fastest being 2GHz (2000 MHz), which was recently launched, thus being the first one to hit the 2 GHz barrier.
The Pentium 4 incorporates a host of new features aimed at allowing it to run at very high speeds along with newer technologies which help it to maximize its throughput & efficiency.
The birth of the new Netburst architecture has led to the introduction of newer technologies such as Hyper Pipelined Technology, Rapid Execution Engine, Execution Trace Cache, Quad Pumped 100 MHz system bus & SSE2, which set this processor a class apart form its earlier cousins.
Lets take a brief look at each of these new technologies:
1. Hyper Pipelined Technology: First of all, the pipeline of a processor is the area where all the instructions are streamed to the processor as it operates. Here in the Netburst architecture, the processor's pipeline consists of 20 stages as compared to 10 stages earlier in the Pentium III (P6 architecture), which is the prime reason for its ability run at higher speeds without a large increase in it's die size. The maximum speed attained by a Pentium III with P6 architecture is 1GHz while that of a Pentium 4 with NetBurst architecture goes upto 2 GHz of which, both are manufacured under 0.18 micron process (0.13 micron process based chips are round the corner!).
However, there is also a disadvantage. Due to the increase in the number of stages in the pipeline, the processor achieves lower number of Instructions Per Clock (IPC) which has been countered by hiking up the clock speed (lowest being 1.3 GHz). A 20-stage pipeline would mean more branch prediction errors in the Branch Prediction Unit (This is the area where the processor tries to guess the course of action based on previous instructions. In case of a wrong prediction, it will have to backtrack and take the correct course which will lead to wastage of clock cycles.), which Intel claimes to have reduced by 30% by gifting the Pentium 4 a better BPU with improved branch prediction algorithms.
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