Method and apparatus for data transmission on a removable and a portable nonvolatile storage medium

摘要

A method of transferring update data from a microcomputer to a memory device having a transportable non-volatile memory median requiring that the transportable non-volatile memory median is divided into a plurality of sectors. Update data is to be written to data sectors of the transportable non-volatile memory median in accordance with a sector map. One of the sectors to be updated is the directory sector and another one of the sectors to be updated is the file access table sector. The microcomputer is programmed to reserve a specified number of sectors as a recovery area wherein some of the sectors of the recovery area are reserved for the sector map and other sectors of the recovery area are reserved for storage of the update data. The microcomputer identifies if a sector map resides in the recovery area. If no sector map resides in the sector map area of the recovery area, the microcomputer proceeds to identify which of the sectors are to be updated and generating a sector map accordingly. If a sector map resides in the recovery area, the microcomputer first writes data from the recovery area to the sectors according to the sector map and then proceeds to identify which of the sectors are to be updated and generating a sector map of the sectors to be updated. The microcomputer then writes the sector map and the update data to the recovery area before writing the update data to the sectors in accordance with the sector map. Once the respective sectors are updated the sector map is erased.