To realize the virtual support of multiple devices by continuously updating items so that the item used last is identified and judging which channel state information item is to be eliminated from a cache.

Whether DMA state information ID is cached or not is judged from a VCI map (S710). When channel information is not cached (S712), channel information is read from a memory, is arranged in the cache (S715) and an operation on a cell is executed (S740). A former pointer in the uppermost entry at. present in a list is updated to indicate the accessed entry (S750). The pointer next to the accessed entry is updated to indicate the uppermost entry at present in the list (S765). The accessed entry functions as the uppermost entry in the MRU list.