Abstract: The hardware semaphore generates an interrupt signal upon a change in ownership status of a shared resource. In particular, the semaphore apparatus generates an interrupt signal when a requesting device or process relinquishes control of a shared resource. By generating a hardware interrupt when a shared resource becomes available, devices or processes that require access to the resource need not repeatedly poll the hardware semaphore to determine if the resource associated with the semaphore is available. In a preferred embodiment, the hardware semaphore apparatus employs a pair of cross-coupled NOR gates for arbitrating between two requesting devices. A pair of rising edge detectors and flip-flops are connected to outputs of the NOR gates for generating the interrupt signal. Other exemplary and illustrative embodiments are described as well.