Patent ID: 8429324

Claim:
A bus-protocol converting device comprising: a primary bus interface controller to which an external-memory control device is connected through a primary bus, the primary bus interface controller including a first-in first-out memory as a communication buffer; a secondary bus interface controller to which an external memory device is connected through a secondary bus; command detecting means for detecting a command sent from the external-memory control device, connected to the primary bus, to the primary bus interface controller; command converting means for converting the command detected by the command detecting means into a command to be sent from the secondary bus interface controller to the external memory device through the secondary bus; status detecting means for detecting a status sent from the external memory device connected to the secondary bus; status converting means for converting the status detected by the status detecting means into a status to be sent from the primary-bus interface controller to the external-memory control device through the primary bus; and a data transfer controller that is provided between the primary bus interface controller and the secondary bus interface controller to perform data transfer between the external-memory control device, connected to the primary bus, and the external memory device, connected to the secondary bus, through a direct-memory-access bus; wherein the data transfer controller uses the first-in first-out memory in a ring buffer, assigns the ring buffer as a virtual memory, directly sends a value of a data transfer size from the external-memory control device to the secondary bus interface controller, executes a bus master direct-memory-access operation once between the secondary-bus interface controller and the virtual memory, and performs bus-protocol-conversion data transfer simultaneously with the execution of the bus master direct-memory-access operation.