FILE AREA ALLOCATING METHOD

PURPOSE:To perform the allocation of a sector at high speed by referring to label display information attached on each sector and retrieving the boundary between the sector on which a label is written and an unused sector by using a binary searching method when the allocation of the sector on which a new label is to be written is performed. CONSTITUTION:A file area allocation control means 7 and a binary searching means 8 are housed in a random access memory 4, and the retrieval, write, and readout, etc., of a file area provided on a DRAW type optical disk 6 are performed via an input/output control part 5. The label display information f1-fN which can identify the sector on which the label is written in advance from the unused sector are attached on each sector. The boundary between the sector on which the label is written and the unused sector can be retrieved at high speed by using the binary searching method while referring to the label display information f1-fN. In such a manner, it is possible to allocate the sector on which the new lable is to be written at high speed.