US Patent 7707448 Deterministic test strand unparking

A circuit for deterministic unparking of a strand of a microprocessor having multiple clock domains is described. The circuit includes a first flip-flop and a second flip-flop. Each flip-flop has a data input connected to receive a respective unpark signal, a clock signal at respective clock frequencies, and a respective enable signal. Each enable signal is generated by a respective logic block, each including a counter and each operating at a respective one of the clock frequencies. The second flip-flop has a data input connected to an output of the first flip-flop, and outputs an unpark signal that is used to unpark a strand of the microprocessor in a deterministic manner.