Abstract: A host device is connected to a storage device via a bus and reads and writes data in the storage device. The host device includes a command transmitter that sequentially transmits a command in a command sequence, which includes a set of commands which do not change data stored in the storage device, and a response receptor that accepts a response from the storage device for each command transmission from the command transmitter and determines whether or not an error exists. An acceptable/unacceptable access determiner provided in the host device enables access to the storage device when a normal response is identified by the response receptor and otherwise determines that access to the storage device is unacceptable. The normal response is when the responses received from the storage device for the transmissions of all commands in the command sequence do not include an error.

Abstract: A host device (1) adds host function information indicating a function of the host device (1) to a command and transmits it to a storage device (2). The storage device (2) receives the command transmitted from the host device (1) and determines whether the function indicated by the host function information can be processed. When the function can be processed, the function is processed based on the command. When the function cannot be processed, no response is returned or error information is returned. Thus, under simple control, it is possible to prevent data destruction by a host device of an old version.

Abstract: A host device transmits a command from a command transmission unit (101a) along a predetermined command sequence. A storage device (2) receives the command in a command reception unit (202a). An access determination unit (202c) determines the sequence of the command transmitted from the host device (1) and determines that reception of the access to the host device (1) is enabled only when the sequence is identical with a predetermined sequence. Thus, with simple control, it is possible to prevent data destruction by a host device of an old version.

Abstract: When a file system control part 155A writes file data into a main memory 142, a file can be easily written continuously and the number of file copy can be decreased at updating a directory entry by writing the file data and a directory entry into different allocation units. In this manner, when using a nonvolatile memory in which physical block size as an erase unit is larger than cluster size, the write performance can be enhanced.

Abstract: A host device (1) adds host function information indicating a function of the host device (1) to a command and transmits it to a storage device (2). The storage device (2) receives the command transmitted from the host device (1) and determines whether the function indicated by the host function information can be processed. When the function can be processed, the function is processed based on the command. When the function cannot be processed, no response is returned or error information is returned. Thus, under simple control, it is possible to prevent data destruction by a host device of an old version.

Abstract: A host device transmits a command from a command transmission unit (101a) along a predetermined command sequence. A storage device (2) receives the command in a command reception unit (202a). An access determination unit (202c) determines the sequence of the command transmitted from the host device (1) and determines that reception of the access to the host device (1) is enabled only when the sequence is identical with a predetermined sequence. Thus, with simple control, it is possible to prevent data destruction by a host device of an old version.

Abstract: When a file system control part 155A writes file data into a main memory 142, a file can be easily written continuously and the number of file copy can be decreased at updating a directory entry by writing the file data and a directory entry into different allocation units. In this manner, when using a nonvolatile memory in which physical block size as an erase unit is larger than cluster size, the write performance can be enhanced.