Antonelli, Terry, Stout & Kraus, LLP
File control method and system for allocating a free block to a file when the previously allocated block is to be written to
 A file control method by which a number of a block first allocated to a file is saved in an external memory and data and a number of a block to be next linked or a flag indicative of an idle block are recorded in each block to thereby restore the file information, and a version of each block is recorded therein to thereby allow easy access to a data block of the specified version. A number of a head block in the file is always saved in an allocated block list of a file information area. The data and the number of the block to be next linked or the identifier indicative of an idle block are recorded in each block of the data storage area. A file control program, when it is desired to add new data to the file, allocates a spare idle block to the file. When file writing operation is interrupted, the head block number and the next block number of each block in the file information area are traced up to the idle block to thereby restore a file information table. 
Hitachi, Ltd.
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G06F G06F G06F Y10S
inventional inventional inventional additional
Nozomu Kumiko Miho Hirofumi
Hirose Yagi Iwanaga Yamashita