1. A test architecture within an integrated circuit, the test architecture comprising:
serial input;
serial-to-parallel circuitry coupled to the serial input and including parallel outputs;
circuitry to be tested, wherein the circuitry to be tested is coupled to the parallel outputs of the serial-to-parallel circuitry;
parallel-to-serial circuitry coupled to the circuitry to be tested;
serial output coupled to the parallel-to-serial circuitry;
a clock input; and
a controller coupled to the serial input, the circuitry to be tested, and the clock input, wherein the controller is configurable to respond to a control bit embedded in a serial scan frame received via the serial input.