An integrated circuit device has boundary scan structure coupled between a test input and the test output. The test register structure is used to shift information from the test input to a test output. The test shift register structure contains a data shift part coupled to connections for a functional circuit under test. In parallel with the data shift part is an instruction shift structure. By means of test control signals it is controlled whether instruction information travels from the test input to the test output through the instruction shift part or through the data shift part. The instruction shift part controls operation of the device in a test mode. A sensor is provided for sensing a physical operating parameter of the device. The sensor has an output coupled to the shift register structure for feeding a sensing result to the test output from the instruction shift part.
