Apparatus and method for testing of new operating systems through priviledged instruction trapping

A method of implementing a privileged instruction that enables the development of new operating systems in user mode. The instruction decode logic includes a maskable interrupt generator that interrupts the processor during the processing of privileged instructions in user mode. An exception handler processes the privileged instruction interrupt and performs a function similar to the execution of the privileged instruction in privileged instruction mode. The combination of the privileged instruction interrupt and the post-interrupt exception handling enables the operating system developer to test new operating systems by laying them over the current operating system.