PURPOSE: To complete the read out when a specific code appears the readout out of a buffer, by storing a specific code to a buffer storage area for writing a data from a file to a prescribed location of the buffer.

CONSTITUTION: All areas of the buffer 2 are filled in by storing a code which cannot be found out in various treated codes, e.g., a specific code FF to a file 4. Further, data for the 1st block's share from the file 4 are stored in order from a prescribed location of the buffer 2, e.g., point P toward the arrow E. Then, since an FF code not in data appears in reading the record unit from the buffer 2, thus the completion of reading for one block's share is recognized. Further, the stored data is read out with the user's program 3. In this case, when the FF code appears, the reading is stopped immediately.