Patent ID: 7818477

Claim:
A storage device, comprising: a storage medium composed of a nonvolatile flash memory for storing data; a buffer control unit including a data buffer for temporarily retaining data to be written transmitted from a host device and a nonvolatile buffer save memory for saving data of said data buffer; a control unit for controlling said buffer control unit; and a control information retaining unit for retaining control information including address information provided from the host device and information for writing data into said storage medium, wherein said control information retaining unit includes: a register for temporarily retaining the control information; and a nonvolatile control information save memory for saving information of said register, and wherein said control unit saves write data retained in said data buffer into said nonvolatile buffer save memory when the host device issues an end command of writing data, wherein said control unit saves the control information retained in said register into said nonvolatile control information save memory, wherein said control unit stores the write data in said storage medium based on information regarding the write data obtained from said host device, and wherein said control unit informs said host device of completion of writing after completion of saving the data.