An apparatus providing for a secure execution environment is presented. The apparatus includes a microprocessor and a secure non-volatile memory. The microprocessor is configured to execute non-secure application programs and a secure application program, where the non-secure application programs are accessed from a system memory via a system bus, and where the secure application program is executed in a secure execution mode. The microprocessor has secure execution mode logic that is configured to monitor instructions within the secure application program, and that is configured to preclude execution of certain instructions. The secure non-volatile memory is coupled to the microprocessor via a private bus, and is configured to store the secure application program, where transactions over the private bus between the microprocessor and the secure non-volatile memory are isolated from the system bus and corresponding system bus resources within the microprocessor.