A magnetic stripe card manual swipe reader (MSR) unit capable of attaching to and communicating with a conventional personal digital assistant (PDA) from various manufacturers, using only the electrical power available as supplied by the PDA device, and capable of effective electrical power management...http://www.google.com/patents/US6944782?utm_source=gb-gplus-sharePatent US6944782 - Magnetic strip reader with power management control for attachment to a PDA device
