View this article at: http://dev.macnn.com/articles/05/11/16/powerbook.safe.sleep Wednesday, Nov 16, 2005 1:45pm New \"Safe Sleep\" mode on ... Apple's latest PowerBooks added a new feature called "Safe Sleep"--similar to the "hibernate" feature on Windows laptops--that enables users to return to the system's previous state, even if the battery runs out or is removed. An online guide explains how to implement software feature on older iBooks and PowerBooks, allowing owners of older Mac laptops to take advantage of the feature (at their own risk). Regular sleep mode works by cutting power to components except for the machine's RAM. Because RAM uses so little electricity and has no moving parts, a machine can operate in sleep for a very long time. But if a battery runs out or is removed, the system's suspended state will be lost. The "Safe Sleep" technology works by recording the machine's RAM contents to the hard disk, which is not affected when power is lost. When the power source is returned, the content is transfered back to the RAM, and the user can resume where they left off.