A data processing system includes a first interrupt controller with an interrupt source interface, an interrupt controller interface, a prioritizer, and an interrupt controller output. The data processing system further includes a processing unit providing an interrupt controller interface. Interrupt requests generated by a first plurality of interrupt sources, a second selected interrupt request, a second priority signal, and a second interrupt source index signal generated by a second interrupt controller are received by the first interrupt controller. From the plurality of interrupt requests and the second selected interrupt request, a first single interrupt request is selected and transmitted to the processing unit along with a first priority signal, and a first index signal. The processing unit initiates an appropriate interrupt service routine on the basis of said first index signal.