STORAGE MEDIUM

PURPOSE:To achieve a high speed for data transfer into an upper apparatus by arranging a memory region wherein reading and writing are possible between a plurality of concentric ring-shaped read-only memory regions, respectively, and storing the updated data in each ring-shaped read-only memory region in the readable and writable memory region in the vicinity. CONSTITUTION:A plurality of ROM regions 2 and RAM regions 1 are provided. One or a plurality of neighboring tracks are arranged in the respective regions. The updated data in the ROM region 2 are stored in the RAM region 1 as close as possible to the ROM region 2. For example, when the data at the positions of the track number 3 and the section number 0 are updated, the newest data are written into the track number 2 and the sector number 11. Thus the times of the seeking are decreased. In this way, the high speed for the transfer of the data into a higher rank apparatus is achieved.