Atom's FSB and Multi-Core Aspirations

All Intel Front Side Buses (FSBs) use Gunning Transistor Logic; it produces a good signal that's clearly capable of reaching incredibly high speeds, presently up to 1600MHz. But remember, Atom isn't about being the fastest, just about being fast enough - leaving some room for improvement here.

A GTL FSB uses on-die termination to deliver a very clean data eye each clock, necessary when operating at very high frequencies. Atom isn't the most data hungry processor in the world and thus it can get by with a 400MHz or 533MHz FSB, thus the GTL FSB ends up being overkill.


Dual Mode FSB 

Atom supports both a GTL or CMOS based FSB, the choice is made during manufacturing and a fuse is blown configuring the FSB for GTL or CMOS operation. When in CMOS mode on-die termination is turned off, the FSB runs at 1/2 the voltage of GTL mode and overall power is reduced. There are no performance tradeoffs to CMOS vs. GTL at the frequencies we're talking about here, the differences are only chipset compatibility and power.

Poulsbo can function in CMOS mode so you can expect Atom processors paired with the Poulsbo chipset to function in this lower power FSB mode. Atom won't be restricted to working with Poulsbo however, and the Diamondville core (Atom for cheap desktops and notebooks) is most likely Atom running in GTL mode so it can work with conventional desktop chipsets.

Atom is multi-core capable but obviously the first incarnation is a single-core design. The first manifestation of a multi-core Atom will be with a dual-core Diamondville due out later this year. Like previous dual-core CPU designs, Atom will place two cores behind a shared FSB. Once it gets an integrated memory controller, the multi-core designs will be more elegant.

Gridless Clock Distribution Poulsbo: An Unusually Revolutionary Chipset
POST A COMMENT

46 Comments

View All Comments

  • FlakeCannon - Wednesday, April 2, 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 2, 2008 - link

    What does an on-die memory controller have to do with ILP? Reply
  • Anand Lal Shimpi - Wednesday, April 2, 2008 - link

    Woops, I've clarified the statement :)

    Take care,
    Anand
    Reply
  • erwos - Wednesday, April 2, 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 2, 2008 - link

    It could always be paired with a different, more capable graphics core. Reply
  • ltcommanderdata - Wednesday, April 2, 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 2, 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 3, 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 2, 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 2, 2008 - link

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

Log in

Don't have an account? Sign up now