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IBM Thinkpad T40 beep with 3 keys pressed simultaneously [keyboard beep key]

Discussion in 'Laptops' started by Haris, Mar 2, 2004.

  1. Haris

    Haris Guest

    My T40 has this annoying habit of beeping if certain combinations of 3
    keys are pressed simultaneouly.

    For example, if I press DER simultaneously by accident, it will beep.
    There's may such combinations, and don't make any sense. I noticed it
    on another T40 as well.

    Has anyone figured out why this happens, and how to turn it off?


    Haris, Mar 2, 2004
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  2. It's a head-detector. When your computer has detected that you have fallen
    asleep on your computer, then it will beep, thus waking you up.

    Another one of those 'thinkvantage' advantages of having a thinkpad!!!

    Duncan James Murray, Mar 3, 2004
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  3. Haris

    Haris Guest

    Funny, but doesn't answer the question.
    Haris, Mar 5, 2004
  4. Exactly the same happens on my old TP 570, too. No way to turn it off.
    Here's an explanation of this phenomenon:


    << Electrically, keyboards are grids of crossed address wires, which
    can be connected together arbitrarily at their crossover points when
    you press keys. Every time you press a key, you connect wires
    together; the keyboard hardware looks at which wires are connected to
    tell which keys are being pressed.

    If more than one connection's being made on a given wire, though, the
    keyboard hardware won't be able to figure out which keys you're
    pressing. If a theoretical keyboard had one horizontal address wire
    for each row of keys, then you wouldn't be able to press any two keys
    on the QWERTY row simultaneously and have anything happen.

    I don't know whether any real keyboards are this simple. I suppose
    some real cheapies may be. Better keyboards split up the 'board into
    separately addressed zones, which may or may not all be composed of
    contiguous blocks of physical keys. There are numerous designs out
    there, and also differently intelligent hardware on the other end of
    the matrix, which may or may not be able to handle more than a given
    number of keys at once no matter where they are.

    There's a specific "too many keys" error that keyboards can report,
    with which the operating system can do what it wishes. I speak from
    recent experience when I say that Windows generally system-beeps
    repeatedly at you when it gets this "cat-on-the-keyboard" error. Some
    keyboards have their own noisemakers and will beep or click at you
    when the error occurs, no matter what OS you're running.

    If I space my hands over my old IBM battleship carefully enough, I can
    press a key with each finger and not get the too-many-keys beep. This
    isn't of much interest, though; if I don't space the keys I'm pressing
    out, I often can't press more than three at a time. Three nearby keys
    at a time is enough for most gaming purposes, though; press any three
    of your WASD keys at once and one of them will be contradicting one of
    the others anyway.

    You can work out empirically which combinations of keys a particular
    keyboard supports, by just fiddling around with a text editor window
    open. For all of the keys except the modifiers (Control, Alt, Shift)
    and other special keys, the last one you pressed ought to repeat if
    the combination's OK, and nothing should happen (possibly with error
    beeps) if you're pressing too many. It's easy enough to do this before
    buying a keyboard, if the store staff will let you.

    My IBM, for instance, lets me press ASD at the same time with no
    problem, likewise SDF, or indeed ASDF together. But not DFG, FGH, GHJ
    or HJK. But JKL is OK again, as is KL;. Not L;', though. Various
    sub-combinations of non-allowed combinations are OK, though; D and F
    and any letter on that row except G are fine. Et cetera. >>

    monty cantsin, Mar 7, 2004
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