1. A tester processing system comprising: a test head; a tester data bus in communication with the test head; a multi-stream switch in communication with the tester data bus; and a plurality of processors in communication with the multi-stream switch; wherein each of the plurality of processors runs a separate instance of tester software, and wherein the multi-stream switch is designed to allow each instance of the test software to communicate with corresponding sections of the test head through the tester data bus without interfering with instances of the test software running on other processors.