interrupt line and the master must also maintain the interrupt line at the idle voltage through a pull resistor if no further service requests are pending in the exemplary embodiment therefore detection of the service request voltage occurs when the interrupt line voltage is detected to exceed a logic high threshold and a detection of the idle state voltage occurs when the interrupt line voltage is detected to have fallen below a logic low threshold other thresholds may be used in some circumstances the two conductor bus 108 transactions include information indicating whether data is to be passed from the master to the slave or from the slave to the master where the direction of data flow being is set by the master device if the slave processor 106 initiates a slave service request and the master processor 104 interrupts the request by initiating a master service request before the slave processor 106 has returned the interrupt line voltage to the idle state the transition from the service request voltage to the idle state voltage is interpreted by the master processor as an acknowledgment by the slave processor 106 to the master service request since the master processor 104 sends information related to the master processor task the slave processor 104 processes the master processor task and initiates another slave service request if the master processor initiates a.