PURPOSE: To improve the efficiency of an information processing by shortening the time for,aking access from a host device to the file of a storage medium.

CONSTITUTION: While controlling a file selector composed of a logical/physical address converter 38 and a scroll timing generator 35 equipped with a file address latch 30, independent file block address spaces are allocated to respective blocks in plural segments constituting a semiconductor memory 18 connected to a host computer inside bus and when a logical file address outputted from the host is coincident with the content of the file address latch 30, the host can directly make access to the file on the semiconductor memory 18. When the required file in a main body DISK memory 5 or all the address spaces of the file block can not be allocated to the semiconductor memory 18, by scrolling the file in the main body DISK memory, the host can perform make access as if all the file data are present in the semiconductor memory 18.