Method and apparatus for preserving changes to data

1. Field of the Invention Handheld computers, e.g. a Palm® Connected Organizer, typically use volatile memory such as random access memory (RAM) to store user data. If the volatile memory of the handheld computer were lost before the data in it is synchronized with the user's computer, then the user's changes would be lost. In order to preserve the changes, records of changes made on the handheld computer can be stored in a non-volatile memory on the handheld computer and/or transmitted over a wireless communication channel to a computer. This computer may house multiple users' data. After a failure of the handheld computer's memory, the contents of the handheld computer memory can be reconstructed using the most recent copy of the data on the user's computer and the records of changes in the non-volatile memory of the handheld computer and/or the computer that is receiving change records over the wireless communication channel. A number of techniques may be employed to control costs associated with using the wireless communication channel such as adding the change records to other packets. Also, rules and schedules can control the use of the wireless communication channel.