A Prelude to Success

This all started back in 2004, in Austin, Texas. Despite the location, I am talking about Intel and not AMD. In 2004, Intel's Austin Design Center was hard at work on another member of the Pentium 4 processor family - codenamed Tejas.

Tejas was scheduled to arrive after Prescott and continue the NetBurst lineage, but as history would have it, Tejas never saw the light of day. The project was canceled and Intel's corporate attention was instead shifted to taking the Pentium M architecture and improving it to be desktop-worthy.

The Tejas team was, as you'd expect, not particularly pleased with their project being canceled. But, as seems to be the case with Intel's best engineers and canceled projects, they channeled their disappointment into passion and excitement for their next design.

I should stop the story here and point out the striking similarity to another Intel success story, that of the original Centrino. Banias was the first Centrino processor, later named the Pentium M. The team that worked on Banias was the same team that worked on Timna, yet another project cancelled very late in the process. After Timna was cancelled the team, working out of Intel's Israel Design Center, went into a brief collective depression for about a month before receiving instructions to work on Banias. Instead of producing something mediocre, the team felt a need to prove something to those who cancelled their beloved Timna project. The result was Banias, which became the Pentium M, led to the Core Duo and eventually gave us the Core 2 family of processors that we love so dearly today.

Back to Austin. We've got a very small team of people who were hard at work on Tejas and now without anything to do. The same sense of proving their worth brew and in 2004 the team received new orders.

The task was to develop a low power, IA (Intel Architecture, read: x86) core for use in a many-core CPU design. Since this core would be used in a many-core CPU, it would have to be very, very low power (you can't have 10s of cores each consuming 100W).


Many-core CPU designs are in Intel's future, Atom has its roots in the many-core initiative 

I asked the design team in Austin if this was a dirty joke played on them by upper management - going from a very power hungry design like Tejas to something that would consume a couple of watts. Apparently during Tejas' design, a smaller team in Austin was doing some pathfinding work, looking at very low power simple cores. Since they spent about a year doing this pathfinding work, the transition from Tejas to something very low power was natural despite what it may seem from the outside.

Many of the architects that would work on this new, low power core actually came from other microprocessor companies. Belli Kuttanna, the chief architect on the core, worked for Sun on SPARC processors as well as Motorola designing elements of PowerPC cores. Belli worked with others from Sun and Motorola, but now all under the Intel umbrella. One of the members of the validation team working on the core was also a former AMDer.

Early 2004 was the inception of the pathfinding effort to investigate what would be necessary to develop this new low power core. The codename for this core was Bonnell, which as I've mentioned before is the tallest mountain in Austin, measuring only 750 ft. The petite mountain was a perfect fit for this new, small core (engineers aren't the most creative with naming ;)).

The first step in the pathfinding effort was to find out if Bonnell could be based on an existing Intel microarchitecture. The small team looked at reusing the Pentium M or the yet-to-be-released Core 2 and some analysis was done on both of these options. It didn't take long to come to the conclusion that it wasn't possible to hit the power and performance targets using an existing design. As Intel discovered with Centrino, in order to target a new market it would need to use a new microprocessor design.

The team went back to a clean sheet of paper and started with the simplest of microprocessor architectures, a single-issue, in-order core and built up from there. The designers kept iterating until the performance and power targets at that time were met. You have to keep in mind that in 2004, even Intel didn't have a good idea of exactly where this core would be used. Imagine going back to 2004 and being expected to design the microprocessor architecture that could eventually be used in something like a third generation iPhone - it's borderline impossible.

By the end of 2004, Paul Otellini gave the Austin team specific direction that the Bonnell core would be used in a standalone CPU - not as a part of a many-core design effort. This CPU would be used in UMPCs (Ultra Mobile PCs) and an even more unheard of creation called a MID (Mobile Internet Device). The many-core designs are still under development and I suspect that the first one we'll see come to fruition is a little gem called Larrabee.

Bonnell was just a core, but when combined with a L2 cache and an external bus interface it became the CPU known internally as Silverthorne. More recently, Intel gave Silverthorne a proper name and called it the Atom processor.

What AMD Taught Me: x86 Everywhere Atom at a Glance
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  • FlakeCannon - Wednesday, April 02, 2008 - link

    This was an absolutely fantastic article as far as I'm concerned. One of the best I've read from AnandTech. I'm truly impressed with the amount of effort and dedication that the engineers at Intel put into the Atom. Thought the consumer may not see its importance today the Atom will continue to develop one throughout the next 2 years and show why this is such a huge step in the right direction. I really think that this article outlines very well the architecture involved and where it intends to lead Intel and others in the future.

    I'm always impressed to see Intel take architecture that was revolutionary in its time 15 years ago in the Pentium and Pentium Pro and resurrect it in modern day fashion with help of the Dothan Pentium M architecture and even things borrowed from the miserable Netburst technology that 15 years later I believe will once again create a product revolutionary in nature. I was never able to appreciate it in the days of the Pentium but certainly can now.

    This is one product I think is deserving of being excited about.
    Reply
  • fitten - Wednesday, April 02, 2008 - link

    What does an on-die memory controller have to do with ILP? Reply
  • Anand Lal Shimpi - Wednesday, April 02, 2008 - link

    Woops, I've clarified the statement :)

    Take care,
    Anand
    Reply
  • erwos - Wednesday, April 02, 2008 - link

    I was thinking that this would be a fantastic platform for making a small, silent HTPC box for doing streaming media, but the lack of 1080p output kills that to a large extent. I know it's not a big priority for the first revision given the UMPC targeting, but I hope the "Atom 2" does try to squeeze that feature in. Reply
  • FITCamaro - Wednesday, April 02, 2008 - link

    It could always be paired with a different, more capable graphics core. Reply
  • ltcommanderdata - Wednesday, April 02, 2008 - link

    It;d be very interesting to see how the 1.86GHz Silverthorne stacks up against a 1.8GHz P4 Northwood, a 1.86GHz Dothan, a 1.8GHz Conroe-L based Celeron, and a 1.8GHz Athlon 64.

    I wonder if Apple is going to refresh AppleTV with Silverthorne since it seems ideal with replace the current 1GHz ULV Dothan in there.
    Reply
  • yyrkoon - Wednesday, April 02, 2008 - link

    Well at least Intel did not name their Atom CPUs the 'Atom Z80' . . . heh.

    Anyways, this is good for our future, as the mITX, and pITX 'systems' now days are still kind of large-ish, and cost quite a bit of money for what they are. Though, I think that putting a web browser on just any old appliance in the house would be way overkill, and possibly a very serious mistake. A TV with a web browser ? An Oven ? Please . . . this is why we have PCs, and micro mobile devices.

    Recently a friend and myself have been working on an embedded project, and I can see the potential here, but a 'problem' does exist. Some of the things you would want to do with such a processor . . . well lets just say there still would not be enough processing power. That being said, I do not see why these could not help make a TVs/HD-DVD player menu operate faster.


    Reply
  • pugster - Thursday, April 03, 2008 - link

    It certainly sounds nice, but the atom processor cost alot because some of the higher end models cost more than $100 each. I find it surprising that their Polosbo chipset is manufactured at 130mm. It probably came from one of their foundries that was due to upgrade to 32mm sometime next year anyways. They could've earily manufactured at 65mm.

    Somehow I don't see their product as mature and maybe the next gen product they would have a cpu and the north/south bridge in the same die.
    Reply
  • lopri - Wednesday, April 02, 2008 - link

    I honestly don't get the excitement. Should I? I mean, I wouldn't feel comfortable with one gigantic company controlling every single electronics in our life. If Intel opens up the X86 and everyone can compete on even end, then maybe. Since that won't happen, the future looks scary enough. Reply
  • clnee55 - Wednesday, April 02, 2008 - link

    NO, how can you get excitement. I am already bored with your conspiracy theory. Let's talk about tecnical issue here. Reply

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