1. An integrated circuit comprising: at least one processor core; at least one second circuit; and a Known Good Code (KGC) source configured to supply KGC to the processor core for execution, wherein the KGC is protected from modification in the integrated circuit and is provided from an authenticated entity, wherein the KGC comprises a device manager configured to manage access to the at least one second circuit, and wherein the KGC comprises emulation code which, when executed on the at least one processor core, emulates a third circuit that is not included in the integrated circuit.