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Discussion in 'Electrical Engineering' started by Tzortzakakis Dimitrios, Oct 24, 2004.

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  1. I am wondering, how does my keyboard manage with 5 wires?It must be encoding
    input in some way, say two is power supply, and three is output.
  2. A PC keyboard I presume you refer to?

    The signal is carried on one line and serially encoded.
    It is actually bi-directional because the computer tells
    the keyboard to turn on/off the caps lock and other LEDs.
    The keyboard doesn't decide to do this itself -- if the
    computer hangs such that the keyboard interrupt routine
    isn't being called, you'll find CAPS-LOCK stops toggling
    the Caps LED, which can be useful to see at how low a
    level a PC is hung.
    A second line is the clock for the serial data.
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