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Windows 2000 is The Borg!

Discussion in 'Misc Electronics' started by Rich Grise, Sep 15, 2003.

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  1. Bob Masta

    Bob Masta Guest

    You can't use instruction timings for delays on any modern CPU;
    they just aren't that predictable. This used to be recommended on
    '286 machines where JMP $+2 was used after I/O instructions to allow
    the slow ISA bus to settle. When '386s came along, you used to see
    strings of JMPs (in BIOS hard drive code, for example) until people
    finally wised up and used hardware timing. I've used it on '486s
    in special cases where I calibrated the delay at the start of the
    program, but it's a real hassle. Hopeless on a Pentium or later.

    Having said all that, instruction delays are still useful in lots of
    embedded processor applications, where they use old-style
    CPU cores that have deterministic instruction timings. And
    there are a _lot_ of embedded systems out there!


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Shareware from Interstellar Research
    www.daqarta.com
     
  2. Aligning code on cache line boundaries, perhaps. Filling to the end of
    code pages. There was a time when NOPs were put in as place-holders for
    self-modified code (another bad idea ;-).

    OTOH, why waste the energy dispatching, executing, and completing a
    NOP. It's wasting system resources (and heat) that could be used for
    real instructions. Architecturally it doesn't do anything (obviously).
    Any inference one makes on the function of a NOP (or any other
    parameter not specified in the architecture) is simply asking for
    trouble. Add in the OoO nature of modern processors; counting on the
    execution time of any instruction/loop gets even more dubious.
     
  3. Indeed. Since the L1 I-caches don't generally have a write port the
    modified code would have to go at least to the L2, address invalidated
    in the L2, and then refetched. Ugly!

    There was a time when self-modified code was common. It's not so
    anymore.
     
  4. John Jardine

    John Jardine Guest

    On the face of it, the 31nS loop time would seem to need ... 31nS divided by
    the Planc time of 5.38e-44 seconds or roughly 5.76e35 no-cycle loops.
    regards
    john
     
  5. Please send me the design of your counter. We can make some
    serious money! ;-)
     
  6. Nope. It was dropped from the pipe (never saw an execution
    unit). It took zero clocks, as long as there wasn't an unusual
    branch around.
    Nope. It wasn't dispatched. This isn't unusual these days.
    Anyone using NOPS, or any other instructions for that matter, for
    timing loops should be taken out and *shot*. There is a reason
    we have timers these days.
     
  7. Joel Kolstad

    Joel Kolstad Guest

    I was reading an article just yesterday that suggested the way to perform a
    delay in C was to code up an empty for loop. I suppose someone using that
    approach also wouldn't know to turn on the compiler's optimizer... which
    would undoubtedly just remove the loop entirely! (Although it might issue a
    warning message if the user were lucky...)
     
  8. On 15 Sep 2003 09:22:17 -0700, (Rich Grise)
    wrote:

    [All BS snipped]
    All your cursing reveals you're a total moron, not a "hacker". If
    you're too stupid to get your computer to work with Windows, try
    Linux. Although I can hardly believe Linux is something you ever heard
    of.

    What the hell is wrong with you people?

    Joe
     
  9. Andre

    Andre Guest

    Nah . It'll never happen.

    No-one can stop the individual taking their equipment apart , not even
    the Government . No matter how many warnings they put on it and/or
    security screws .
     
  10. Andre

    Andre Guest

    Dammit, we fought two world wars to stop these kinds of idiots . :(

    ....

    -A
     
  11. To hell the law! How many licensed copies of W2K+XP are in use? How many
    unlicensed are? Do you really think that a federal law will be effective
    unless you're going to attach a goddamn CIA agent to every man everywhere
    in the world. As with the hardware, you'll always be able to assemble a
    working PC by buying each card/component separately even if (and this tends
    to be true nowadays) the components have been made not within the country
    you live in just because it is more profitable for those companies to
    assemble different parts at different locations and sell them without
    worrying about who buys them and what for he uses them. Modern hardware is
    far too complicated to be easily tampered with, so there is no point in
    attempting to reverse-engineer e.g. an NVidia gfx card. Did you know that a
    law exists (Sorry, I forgot in which jurisdiction) that requires a hacker
    to set some sort of 'i am a hacker' flag during login to the ISP. Now tell
    me, what use will be of this law. It's obvious, a law is far not everything
    and there is a vast difference between things allowed and those done. As
    for your 'note to spammers', do you think someone using an open-relay
    server in Ho-Chi-Mingh City (or wherever) will care about a Washington
    State Resident?

    Having all this said, I apologize for the language used, I just had to
    comment on the omnipotence of law and what it appears to me.
     
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