IC CARD

摘要

PURPOSE:To recover the lost contents of a directory pointer with a simple processing operation by providing the information showing the length of directory at the head of each directory and recording each directory so as to set the head of each directory at a position close to a 2nd address. CONSTITUTION:The data are read out of an address (y) for each byte in the opposite direction. Thus the byte data on the length of a directory A included in an area ID is obtained. Then it is possible to recognize a fact that an address (a) obtained by subtracting the length of the directory A from the address (y) serves as the head address of a directory B. Then the data are read out of the address (a) for each byte in the opposite direction. Thus the byte data on the length of the directory B is obtained. As a result, the address position of the directory recorded last can be confirmed even if the contents of a directory pointer are lost by some accident. Then the lost contents of the directory pointer can be recovered with a simple processing operation.