INT 33h,  06h (6)        Get Button Release Information

    Return information about button state and number of button releases.

       On entry:      AX         06h
                      BX         Button

       Returns:       AX         Button Status
                      BX         Count of Button Releases
                      CX         Cursor Position (hor) at last Release
                      DX         Cursor Position (ver) at last Release

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    Function 6 returns:

    . The current status of the specified button.

    . The number of times this button was released since the last call to
      this function.

    . The horizontal and vertical coordinates of the cursor the last time
      this button was released.

    The value in BX specifies which button is checked. If this value is 0,
    the left button is checked. If this parameter is 1, the right button is
    checked.

    The button status is a single integer value. Bit 0 represents the left
    button, and bit 1 represents the right button. Theese bits are 1 if the
    corresponding button is down, and 0 if it is up.

    The count of button releases is always in the range of 0 to 32767.
    Overflow is not detected. The count is set to 0 after the call.

    The values for the horizontal and vertical coordinates are in the ranges
    defined by the virtual screen. These values represent the cursor
    position when the button was last released, not the cursor's current
    position.