Function 08h            Read Keyboard without Echo

    Waits for a character from the standard input device. Does not
    echo, but does check for Ctrl-C.

        Entry   AH = 08h

        Return  AL = Character

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    If no character is available this function waits until one is
    available.

    If the character read from the keyboard is an extended key code
    (for example, if the user presses one of the function keys), this
    function returns 00h and the program must call the function again
    to get the second byte of the extended key code.