INT 33h,  00h (0)        Mouse installed flag and reset

    Returns the current status of the Mouse hardware and software

       On entry:      AX         00h

       Returns:       AX         Mouse Status - 0 if not installed
                                                -1 if installed
                      BX         Number of Buttons

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    The mouse status is 0 (false) if the mouse hardware and software are
    not installed or -1 if the hardware and software are installed.

    The function also resets the mouse driver to the following default
    parameters:

        FUNCTION                                PARAMETER
      ------------------------------------------------------------------
        cursor position                         screen center
        internal cursor flag                    -1 (not displayed)
        graphics cursor                         arrow/(-1,-1)
        text cursor                             inverting box
        interrupt call mask                     all 0 (no interupts)
        light pen emulation mode                enabled
        mickey/pixel ratio (horizontal)         8 to 8
        mickey/pixel ratio (vertical)           16 to 8
        min/max cursor position (horizontal)    depends on video mode
        min/max cursor position (vertical)      depends on video mode