A system (2) can include a processing core (6) to execute machine readable instructions. The system (2) can also include a memory (8) accessible by the processor core (6). The memory (8) can include preprogrammed test data (10) that characterizes one of an impedance of a processor (3) and a current output to the processor (4) during execution of a test routine. The processor (4) can include the processing core (6) and the one of the impedance of the processor (4) and the current output to the processor (4) is based on a power measurement taken during execution of a test routine. The power measurement can be taken with a current sensor that is at least one of lossy or at least about 98% accurate.