X-bit labs

Prescott: The Last of the Mohicans? (Pentium 4: from Willamette to Prescott)

Category: CPU

by Victor Kartunov

[ 05/25/2005 | 11:45 AM ]

We are proud to offer you the most detailed article on NetBurst architecture and its peculiarities. We applied our own approaches and methodology to studying the NetBurst architecture and we are ready to share some facts and details, no one has ever discussed before. This is the first article of the trilogy: more exciting stuff is coming within the next couple of days with absolutely exclusive material about what actually slows down Pentium 4 processors. You will not believe your own eyes when you see this! So, stay tuned and don’t miss the three exciting parts of X-bit’s indepth NetBurst Architecture investigation!

Table of contents:

• Chapter I: What This Article Is About and Why We Decided to Write It
  
• Chapter II: Goals and Prospectives of Processor Micro-Architecture Development
  
• Chapter III: Introducing New Terms in the Micro-Architecture Field
  
• Chapter IV: Arithmetic Logic Units in NetBurst Micro-Architecture
  
• Chapter V: Cache Hierarchy
  
• Chapter VI: Pentium 4 Pipeline Architecture
  
• Chapter VII: Hyper-Threading Technology
  

Chapter I: What This Article Is About and Why We Decided to Write It

It has been known for a long time that there are three things a man can watch for ever and ever: running water, burning fire and working people :) While we don’t dare deny the first two statements, for the IT article readers the third “universal truth” can be transferred into the following: we can endlessly argue whether Pentium 4 is a “good” or a “bad” CPU.

It is true, there are very few processor architectures in the world, which have caused as much of a discussion, as NetBurst micro-architecture, which is represented by the Intel Pentium 4 processors. These are the CPUs everybody have heard of today. The arguments about the advantages and drawbacks of this micro-architecture are still in full swing nowadays for multiple reasons: the architecture was revealed at a difficult moment for Intel, for the first time the performance of mass processors depended a lot on the optimizations for each specific architecture, the end-users appeared direct participants of the “megahertz race” for the first time also. And later on this race resulted into the decision to completely give up the frequency as a universal and adequate performance index.

All these factors have definitely affected the arguments. We in our turn also got carried away by the flow of these discussions: each of us has written at least one 1-mile long post in the forums, trying to prove his point. But the great variety of diverse opinions indicated evidently that not everything is smooth and clear in the description of the new micro-architecture. So, all of us decided to put an end to this endless argument and find out what the Intel Pentium 4 processor actually is.

Now let me introduce the team of people hidden behind this mysterious “we”. Maybe some of you will recall the articles devoted to AMD Athlon 64 (Opteron) processor micro-architecture, which were written by the same team of people we would like to once again introduce to you today. Please meet (in alphabetical order):

• Ilya Gavrichenkov aka Gavric
• Jan Keruchenko aka C@t
• Vadim Levchenko aka VLev
• Andrey Lykov aka ISA_user
• Igor Pavlov aka lkj
• Sergey Romanov aka GReY
• Ilya Vaitsman aka Stranger_NN
• Malich Yury aka Yury_Malich
• Sergey Zagursky aka McZag

This way, the entire discussion promised to be (and finally turned out) really exciting. And the results of this discussion have been summed up for you by the “dedicated typist” Victor Kartunov aka matik. This is the easiest way of all to make him do something for the best of the human kind :)

I would only like to add now that while we were working on the materials for this article we once again were very sincerely amazed at the sophisticated imagination of the engineers and developers. So, Welcome into Intel Pentium 4!