An arrangement controls an IC designed with multiple “core” circuits, such as multiple CPUs, with each core circuit including its own TAP controller. According to one example embodiment, multiple test-access port (TAP) controllers coupled to a common interface are controlled by adapting each TAP controller to receive input signals, determine if the TAP controller is enabled, and generate status signals and test signals. An output circuit responds to the TAP controllers by outputting one of the test signals respectively provided by the multiple TAP controllers, and a link module is used to maintain one of the TAP controllers enabled at a given time. The above-embodiment is useful, for example, in connection with IC applications that require an increasing number of core circuits without increasing the circuit area of the IC and/or the number of IC pins, and can be implemented to avoid changing existing structures of TAP controllers.