Patent ID: 7984231

Claim:
An information recording medium access device configured for accessing an information recording medium, including a nonvolatile memory, wherein said nonvolatile memory includes: a data recording area composed of a collection of a plurality of clusters, each cluster of said plurality of clusters having a unique cluster number; and area management information holding a plurality of pieces of entry information, each piece of said plurality of pieces of entry information corresponding to a cluster, wherein said area management information has a plurality of area management blocks, each of said area management blocks is composed of a first constant number of pieces of said entry information having a first consecutive number of clusters, wherein said area management information has a plurality of slots, each of said slots is composed of a second constant number of pieces of said entry information having a second consecutive number of clusters, and wherein said information recording medium access device comprises: an area management block controller configured for determining a slot as an empty slot when the slot has empty clusters of a number equal to or greater than a second threshold value in clusters included in the slot, and configured for determining the area management block as an area into which data can be written when a number of empty clusters included in all empty slots in said area management block is equal to or greater than a first threshold value; and a recording controller configured for writing file data to areas of said nonvolatile memory corresponding to said area management blocks which have been determined as areas into which data can be written.