AH = 12h
Return: AL (same as for AH=02)
           bit 7: Ins ON
           bit 6: CapsLock ON
           bit 5: NumLock ON
           bit 4: ScrollLock ON
           bit 3: Either ALT key down
           bit 2: Either CTRL key down
           bit 1: Left shift key down
           bit 0: Right shift key down
        AH
           bit 7: SysReq key down
           bit 6: CapsLock key down
           bit 5: NumLock key down
           bit 4: ScrollLock key down
           bit 3: Right Alt key down
           bit 2: Right Ctrl key down
           bit 1: Left Alt key down
           bit 0: Right Alt key down
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