Method and apparatus for conserving power on a multiprocessor integrated circuit

Claim 1

A multiple processor integrated circuit comprises: a first processor coupled to a first cache; a first interface coupled to receive memory references that miss in the first cache; a second processor coupled to a second cache; a second interface coupled to receive memory references that miss in the second cache; common circuitry coupled to the first interface and to the second interface; a first power terminal coupled to provide power to the first processor; a second power terminal coupled to provide power to the second processor; a third power terminal coupled to provide power to the common circuitry; wherein the common circuitry comprises a memory bus interface; wherein the first interface is configured to permit operation of the second processor when the first power terminal is not powered; wherein the second interface is configured to permit operation of the first processor when the second power terminal is not powered; and wherein the first interface is designed such that no signals driven by gates powered by the third power terminal are connected to any P-diffusion located in an N-well that is electrically connected to the first power terminal.