The PowerBook Sudden Motion Sensor
Apple added a feature called Sudden Motion Sensor (SMS) to the PowerBook line in early 2005. The sensor attempts to prevent data loss by parking the heads of an active disk drive after detecting a "sudden motion", which could be due to strong vibrations or a fall.
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While the PowerBook only uses the AMS as a defensive measure to prevent accidental damage to the disk drive, such sensors could have a variety of uses. In particular, they have been considered as alternative input methods in user interfaces for video game controllers, phones, PDAs, and other mobile devices. While it is to be seen if they will be successful in these areas, such use at least has a novelty value.
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