Patent ID: 6157978
Filing Date: 2000-12-05
Classification: G06F

Abstract:
A cascaded arbiter comprising:a plurality of request inputs from real-time agents that must be serviced periodically after a loop period of time;a plurality of request inputs from non-real-time agents that can be serviced after irregular periods of time;a request input from a super-priority agent that must be serviced initially after a short period of time being less than the loop period of time;a fixed sequencer, coupled to the plurality request inputs from the real-time agents, for granting access to a shared resource to each of the real-time agents in a predetermined sequence;a phantom-slot inserter, coupled to the fixed sequencer and to the request input from the super-priority agent, for inserting a phantom slot for servicing the super-priority agent into the predetermined sequence, the phantom slot being inserted after an initial request is received so that the super-priority agent is serviced initially after the short period of time being less than the loop period of time;a final-slot signal, generated by the fixed sequencer after all real-time agents activating a request input are serviced by granting access to the shared resource;a timer, coupled to the fixed sequencer, for counting a final period of time from activation of the final-slot signal, the timer generating a time-out signal when the final period of time counted reaches a predetermined timeout value; anda priority arbiter, coupled to the plurality of request inputs from non-real-time agents and coupled to the fixed sequencer, for granting access to the shared resource to non-real-time agents in a priority order, the priority arbiter granting access after receiving the final-slot signal from the fixed sequencer, priority arbiter not granting access after the time-out signal is generated by the timer;whereby the super-priority agent is serviced initially within the short period of time.