FILE MANAGING DEVICE

PURPOSE:To execute a file retrieving operation at a high speed by developing a file memory of an external storage device onto a main memory and managing it so that many files can be set simultaneously to an open state. CONSTITUTION:In an external storage device 3, a file used for an application program 1 is stored, and as for a file area 5, when a file which becomes an object to be processed is open, an area is provided on a main memory. This area is generated at every file, and file data is stored therein. A file input/output program 2 executes a data transfer between the external storage device 3 and the file area 5, and between the file area 5 and a buffer of the application program 1, based on a parameter given from the application program 1 and management information of a file management table 4. As for the application program 1, a file access to the external storage device 3 is executed through the file input/output program 2.