What is the difference between processor architectures?

Reý Aetar September 29, 2012

What is the difference between processor architectures? For example, if there are two 1 GHz processors with similar cores and clockrate, but one is ARM and one is Intel Atom, why is one better than the other?

  1. dhanunjayarao chunduri
    October 6, 2012 at 2:10 am

    the manufacturing way and used components of the processors are variants. that's the reason performance variation.

  2. Jacob
    October 3, 2012 at 5:47 am

    In very simple terms an ARM processor does not have the computing capabilities of an Intel Atom processor.An Intel Atom processor can run more resource hungry applications.

  3. Ahmed Khalil
    October 2, 2012 at 8:11 am

    Simply core structure is same but instructions sets which is supported is difference form one to one and also heatting issue and power consumbusion

  4. Rob Hindle
    September 30, 2012 at 10:47 am

    Actually the specific question was about ARM and Intel Atom. There the story is a bit different. Intel see ARM as a threat, they look at the 15 billion ARM chips out there with some envy.
    Atom is their response. It does have a RISC core but runs x86 derived microcode (so it will run MS Windows programs, a big advantage over ARM) so there's a conversion layer adding some complexity. (In fact Intel do make quite a lot of use of RISC concepts for various roles within their entire chip family.)

    It's much harder to get Windows code to run on ARM - there is an ARM version of Windows 8 but it is limited compared with the x86 version. Microsoft did that in recognition that if they want to get Windows 8 onto mobile phones they need it to run on ARM.

    Intel have a lot of problems.
    If they make the Atom too good computer makers will start using it instead of their more expensive chips.
    Atom performs better than ARM in many benchmark tests but benchmarks are artificial and in real-life applications the differences are much less significant.
    Intel are now getting close in many respects - but not price or third party customisation.
    Manufacturers have been working with ARM for a long time now and Atom would need a very powerful advantage to induce them to switch.
    ARM is a design licensing model, any chip maker who pays the license fees can build their chips. ARM work with them and encourage and support customisation. Intel are less flexible.
    ARM and their partners continue to improve innovate so Intel have to hit a moving target.
    Some of the more powerful versions of ARM chip are invading Intel's more traditional markets (like PCs and servers) too but never neglecting the market for cheap and simple chips. There is a big market for super low power usage chips where speed is either not important or is only needed for brief periods of activity then virtually hibernate to conserve batteries.

  5. Rob Hindle
    September 29, 2012 at 12:33 pm

    Intel processors are very complex. This type of processor is known as CISC (Complex Instruction Set Computer)
    ARM is a lot simpler. Known as a RISC (Reduced Instruction Set Computer)

    The most powerful Intel chip has over 2.5 billion transistors
    The ARM processor core only has around 35,000

    That means the cost of production of an Intel chip is much higher and it uses more electrical power.

    The result of that is that ARM is immensely popular in applications where low cost and low power requirements are important. Many people in developed counties will own dozens of ARM chips hidden away in all kinds of devices, most computer hard disks are conrolled by an ARM chip for example. There are now twice as many ARM chips as people on the planet!

    You might ask what benefit derives from the higher complexity of Intel chips. There is no easy answer, it starts to get a bit technical but to give you an idea of the kind of difference you might find between RISC and CISC technologies:

    Suppose the task is "multiply 1000 by 1000" a CISC might have dedicated multiplier circuitry to handle the task. RISC might instead add 1000 together 1000 times. (Note most ARM chips do have a multiplier, this is only intended as a simple illustration of the kind of difference between CISC and RISC).

    The RISC approach might be slower but that is offset by its simplicity and the fact that when you analyse program code you find that the need for, say, a multiply operation is only a very small percentage of tasks required of the processor.

    In the Intel world there has long been a focus on clock speed and yet ARM chips running at much slower clock speed can match Intel. The first version of the ARM chip appeared in the Acorn Archimedes computer many years ago. Someone wrote a PC emulator for the Archimedes and in many circumstances PC programs would run as fast on Archimedes as on PC despite the overhead of emulation software.

    ARM don't make chips, they design the core and license it to other manufacturers who often add their own specialist circuitry. The Broadcom chip used in the Raspberry Pi £30 computer has an ARM core but they have added HD video processing (among other things) , the original target market for the chip was multimedia devices including iPod and mobile phones.

    • HLJonnalagadda
      September 30, 2012 at 7:40 am

      And I only managed to say that there is no bootloader in ARM. Thanks a lot for the answer, was very informative.

  6. Vijaynand Mishra
    September 29, 2012 at 9:31 am

    Processor is the subset of ARCHITECTURE ...

  7. HLJonnalagadda
    September 29, 2012 at 6:03 am

    Arm loads the kernel directly while Intel X86 follows the bootloader way, like the way Windows boots.
    Would be exciting to see Windows 8 tablet on ARM.

  8. HLJonnalagadda
    September 29, 2012 at 6:00 am

    Thought the idea behind asking here was that the quality of solution given out was higher!

    • Rob Hindle
      September 29, 2012 at 11:06 am

      Disappointing isn't it. Nikhil Chandak is currently (29/9 mid-day UK time) showing #3 genius of the week for his valuable contributions like those two. As a search only finds 6 items from him(?) I guess most get deleted by admin - but he still keeps the profile upgrades.

      Maybe the "Get Points" page should be updated to say "No need to say anything useful, just add facile comments wherever you can."

      • HLJonnalagadda
        September 29, 2012 at 12:41 pm

        That is very true! I think the awarding system needs a rethink, if only to curtail such comments.

      • Rob Hindle
        September 29, 2012 at 9:26 pm

        UPDATE: Just to clarify for any confused people reading HLJ's posting and my response. Someone had posted two replies here, one saying something like "Do a Google search" the next "Do a Yahoo search".

        Looks like admin have deleted them now.

  9. Alan Wade
    September 29, 2012 at 5:41 am
  10. Dimal Chandrasiri
    September 29, 2012 at 4:31 am

    I could've just copied the answer bt, here is the best answer I could find! hope you get the idea! :)


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