Assuring data read/write operation in an electronic appliance

Abstract

In a communication system, when data is read/written from/into a memory contained in a recording medium employed in one electronic appliance by another electronic appliance via a communication control bus such as the IEEE-1394 serial bus, the data read/write operations can be assured. At least one electronic appliance manages the below-mentioned items (1) to (5) when at least one electronic appliance receives commands transmitted when another electronic appliance executes data read/write operations to the storage element; (1) a first electronic appliance is brought into an open state by accepting an open command while being under a close condition; (2) a first electronic appliance is maintained in a close state by accepting a close command while being under a close condition; (3) a,first electronic appliance memorizes the identity of a second electronic appliance which has transmitted an open command when in an open condition; (4) when a first electronic appliance accepts a read/write open command from a third electronic appliance other than the memorized second electronic appliance under a read open condition, the first electronic appliance forcibly closes the read open condition; and (5) when a first electronic appliance receives one of a read open command and a read/write open command from a third electronic appliance other than the memorized second electronic appliance under read/write open condition, the first electronic appliance returns a reject response to the third electronic appliance issuing the read/write open command.