INT 15 - SYSTEM - POINTING DEVICE BIOS INTERFACE (PS) - ENABLE/DISABLE
        AX = C200h
        BH = new state
            00h disabled
            01h enabled
Return: CF set on error
        AH = status
            00h successful
            01h invalid function
            02h invalid input
            03h interface error
            04h need to resend
            05h no device handler installed

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