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x86 architecture concepts

Discussion in 'Embedded' started by Mouarf, Feb 23, 2005.

  1. Mouarf

    Mouarf Guest

    hello all,

    could someone give me a good link on a page that describes the x86
    architecture main concepts and why it is so different from other
    architecture like ARM, PowerPC, alpha....? What are the main markets these
    architecture target to?

    If you also could give me a good link to these architectures too I would be
    really pleased.

    Mouarf, Feb 23, 2005
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  2. Mouarf

    David Guest

    Try: www.google.com

    Once you have more specific questions, try again, but in a relevant

    And if it is homework (as this appears to be), say so - there are plenty
    of people on usenet willing to help you learn, but very few willing to do
    your homework for you.
    David, Feb 23, 2005
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  3. Google ?

    Rene Tschaggelar, Feb 23, 2005
  4. Mouarf

    Mouarf Guest

    If you do not have better answers, please don't answer or answer google with
    the relevant keywords....

    If you feed google with words around x86 you get a jungle of irrelevant
    pages. My last homeworks date very far away and I'm sorry to inform you that
    the question is not trivial. Even if I was a student, of course all answers
    are available on the web, in this case, why usenet exists?

    I asked about the concepts that characterize the x86 architecture (and also
    ARM, alpha...) not the instruction set and not the vendors of x86 stuff like
    google like to give.

    I other terms, what x86 means? Idem for PowerPC, alpha.

    Is this just a brand of Intel?

    Is it a core that use the same instructions as the Intel 86 processors?

    When we look for low power 32bit µC, why don't we say first x86 rather than
    ARM (what makes ARM architecture low power comparing x86)?

    Best regards
    Mouarf, Feb 23, 2005
  5. Mouarf

    CBFalconer Guest

    It starts in the data sheets for the 8008 cpu, circa 1970. By 1973
    we had the more or less mnemnonic compatible, register compatible,
    but not binary compatible, 8080 architecture. By about 1978 this
    had evolved into the mnemnonic and register but not binary
    compatible 8086. From then on binary compatibility has been
    maintained, and this is the primary reason for the wide use of the
    architecture today. Software costs more than hardware.

    I seem to recall that the fastest 8008 instruction required about
    38 uSec. That's micro, not nano. It addressed a full 16 kByte
    memory space, 8 input ports and 16 output ports. It could not save
    its state on an interrupt, and had an inaccessible 8 deep call

    Some informative links:
    CBFalconer, Feb 23, 2005
  6. Mouarf

    Mouarf Guest

    according to you, x86 architecture is only an instruction set?
    Mouarf, Feb 23, 2005
  7. Partly, because it was designed by a company other than those that
    designed ARM, PowerPC and Alpha. Partly, because x86 existed way before
    the said architectures.

    ARM: http://www.arm.com
    PowerPC: http://www.ibm.com
    Alpha: http://www.dec.com

    (Some links might be obsolete)

    Vadim Borshchev, Feb 23, 2005
  8. That's why they don't mention it's homework...

    After a good round of getting usenet to do the homework some folks
    then get a job and seem expect usenet to now do their job for them.
    Nicholas O. Lindan, Feb 23, 2005
  9. Mouarf

    Mouarf Guest

    and why it is so different from other
    I'm not sure, see the PXA processor from Intel that use ARM
    Mouarf, Feb 23, 2005
  10. No, Mouarf, you have it arse-backwards. It is up to _YOU_ to provide
    real questions, not your homework assignment. If this isn't your homework
    question, then your question appears to indicate you may not be qualified
    for the work you are doing.

    Go google -- what you _need_ to learn is how to limit searches so you
    only get the information you want.
    Nicholas O. Lindan, Feb 23, 2005
  11. Mouarf

    Mouarf Guest

    " why it is so different from other
    architecture like ARM, PowerPC, alpha....? What are the main markets these
    architecture target to?"

    Those 2 questions are real questions and if I would have been qualified I
    would certainly not ask questions since I'd know the answers.

    "your question appears to indicate you may not be qualified
    for the work you are doing."

    According to you, we must work on this area to be allowed to ask
    questions??????????? I'm only curious about what differs from an
    architecture to another, and what an "architecture" exactly means.

    Anyway, if I ask unreal questions, consider that you have no need to answer.
    "Google is your friend" is the best answer when someone is able to answer
    the question.

    I really wonder what usenet is for...........
    Mouarf, Feb 23, 2005
  12. Mouarf

    Kelly Hall Guest

    Please don't toppost.

    Given that an instruction set defines all of the visible registers and
    operations, what else do you need to define an architecture?

    Kelly Hall, Feb 23, 2005
  13. Mouarf

    Mouarf Guest

    visible registers and operations refers to software side, is there a
    hardware side hidden in the word "architecture"?

    Comparing to ARM architecture which is known to be lower power than x86 (at
    equivalent processing power), I really believe that the different
    instruction set registers are not the cause of this power consumption
    Mouarf, Feb 23, 2005
  14. Non-sequitor.

    Certain ARM _implimentations_ are lower in power consumption
    than certain equivalent-throughput IA32 _implimentations_.
    And I believe I'm rich and famous.

    Some architecures are simpler to impliment than others and
    require lower clock rates and fewer gates to acheive a given
    throughput. Lower clock rates and fewer gates generally means
    lower power dissipation.

    Low power, high throughput, and simple implimentations were
    just not critera for the IA32 architecture. They _were_
    criteria for the ARM architecture (and for most other sane

    Therefore it's much easier for an ARM implimentation to acheive
    decent throughput with low power consumption.

    The IA32 architecture is a huge pile of kludges on top of a
    base of bogus backwards-compatibility requirements.

    Nobody gave a shit that the 8086 mnemonics and register layout
    were reminiscent of (but incompatible with) the 8080. But,
    Intel sacrificed all sorts of practical things to acheive that
    stupid, useless familiar-but-not-compatible relationship
    between the 8080 and the 8086. It was a horrible decision for
    which the personal computer industry has suffered immeasurably
    for the past 20 years.
    Grant Edwards, Feb 23, 2005
  15. Absolutely. PXA is based on XScale (micro)architecture, which is in turn
    "ARM Architecture 5TE", by ARM nomenclature.

    Your original question was about x86, which is completely different can of
    worms. It all has started the day Intel decided to ..ermm.. "extend"
    their i8080 processor and make it 16-bit. The new i8086 processor had
    inherited the odd registers functionality and names. Subsequent family
    members (286, 386, 486, 586 aka Pentium, 686 aka PentiumII) just added to
    the mess. Due to the numbering convention this whole line is referred to
    as "x86".

    As Intel produces Itanium (or do they still?), the "x86" get another name,
    "IA32". Itanium, for it's 64-bit nature, is named "IA64".

    And now ask somebody about i8035 or i8051 :)

    Vadim Borshchev, Feb 23, 2005
  16. Mouarf

    CBFalconer Guest

    *** Rude topposting fixed ***
    Please don't toppost. Your answer goes AFTER (or intermixed with)
    the quote, with irrelevant material snipped out. This makes the
    article a coherent whole.

    If and when you are accused of being off-topic, it is better to
    explain the misunderstanding (if any) and accept the resultant
    consensus than to come back with a snippy answer which is sure to
    offend someone. I already gave you an answer in the light of the
    history of the X86 chips.

    The X86 chip line has done a remarkable job of expanding
    capabilities in a downward compatible manner. This is not really
    conducive to power consumption reduction. Chips such as the ARM
    and the TI 430 are not saddled with these requirements, and can
    concentrate much better on the power problem. Todays X86 chips are
    routinely dissipating in the order of 100 Watts, while other
    systems are in the milliwatt region. Not too long ago the idea of
    dissipating 1/2 watt in a CPU was already ridiculous.
    CBFalconer, Feb 23, 2005
  17. Mouarf

    Mouarf Guest

    Some architecures are simpler to impliment than others and
    OK I had this idea before (but I wanted to know, I what the x86 architecture
    is more complex, because there are much more instructions?).

    Do you have an idea how National Semiconductor succeeded in strongly
    reducing the power consumption of their Geode processor (now AMD) which is
    called to be a x86 processor, architecture complexity is the same as Intel's
    one and the silicon technology not that different.?

    One other thing, I don't really understand how the Crusoe processors from
    Transmetta that emulates a x86 processor by a software in RAM are the x86
    lowest power consumers. The clock speed is up to 1GHz (I don't know the
    equivalent frequency for non emulated x86 processors) and the power
    consumption ridiculous although there is an overhead consumption caused by
    the software emulation. Do you have an idea about that?

    Best regards
    Mouarf, Feb 23, 2005
  18. Mouarf

    Mouarf Guest

    Subsequent family members (286, 386, 486, 586 aka Pentium, 686 aka

    You mean that the only way for non Intel processors (AMD's one, Crusoe,
    Geode) to be called x86 is to have the same instruction set and main
    registers as Intel's x86?

    Wasn't there any patent on the Intel x86 instruction set that did not allow
    any other company to build x86 processors?
    Mouarf, Feb 23, 2005
  19. More instructions, more complex instructions, registers with
    special meanings, etc.
    IIRC, the Geode uses fewer transisters and a simpler microcode
    engine that's optimized for the frequently used IA32
    instructions. Less frequently used instructions take a bit of a
    performance hit. For a given clock speed the Geode is quite a
    bit slower than a Pentium (maybe half the throughput), but the
    simpler design results in far lower power.

    National cared more about power than raw throughput.

    Intel cares more about raw throughput than power.

    Intel could probably make a lower power IA32 if that's what the
    market wanted. However, it's much easier to make a low-power
    ARM, so if you want low power Intel will justifiably try to
    sell you a StrongARM part rather than an IA32 part.
    Mostly because they actually care about being low power.
    Have you read the papers Transmeta put out on the topic?
    Grant Edwards, Feb 23, 2005
  20. Yes. The proper term for the 32-bit group of the x86 family is
    IA32. If that's what you're talking about (rather than the 16
    bit or 64 bit parts), you should say IA32.
    Other companies built x86 processors.

    That pretty much answers your question about the existence of
    _any_ X where X would not allow other companies to build x86
    Grant Edwards, Feb 23, 2005
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