A method is provided for creating a plurality of partitions on a removable medium of a removable device connected to a computer system. When the computer is started (S1), the operating system and a device driver communicate with each other (S2). The device driver provides a plurality of drive letters for the removable device, so that the media is divided into partitions corresponding to the number of the drive letters. A drive for a media with fewer partitions is regarded to have no media loaded.