Abstract: A hand held device, much like a cell phone or PDA, contains both a data server and a data client along with the voice messaging of a cell phone. The data server communicates through a TCP/IP stack with a local computing system via IR, short distance wireless, a serial bus or Ethernet. The data client communicates with a remote server via a voice network or wireless to the Internet also via a TCP/IP stack and a wide are network. Spare network bandwidth may be used for transferring information. The information may include emails that are received and stored for later review for ultimately transferring to a local computer. Status may include knowing available memory and message sizes. Message that are too large may be noted for later retrieval. On-board memory includes RAM. ROM, and removable modules that may be physically removed and run at a local computing system.

Abstract: A memory management system for random access memories employs a novel B-tree structure to map physical memory locations to logical addresses. In the preferred arrangement each key in the tree structure contains the physical address corresponding to the logical address identifying the key and also contains the size of the data block at that address. The invention also provides a novel arrangement for updating B-trees in response to changes in the keys. The tree buckets containing modified keys are recorded in storage locations other than the locations containing the keys prior to modification. Thus, until the modification of the tree is complete, the system contains a record of the entire tree structure prior to the beginning of the modification.