Patent ID: 7171546

Claim:
An apparatus for extending the functionality of a processor to that of an upgraded CPU, having an upgraded native instruction set, including at least one new native instruction, the apparatus comprising: the processor configured to process data structures comprising executable and operational data, the processor having an old native instruction set corresponding thereto, included as a subset of the upgraded native instruction set, and not including the at least one new native instruction; and a memory device operably connected to the processor and configured to store the data structures, the data structures further comprising: a CPU extension module configured to enable the processor to process, rather than reject, the at least one new native instruction, and the CPU extension module further configured to intervene upon detection of the at least one new native instruction, to selectively provide alternative instructions in terms of the old native instruction set, to render the processor indistinguishable from the upgraded CPU to software processed thereby, and a stack wherein the processor is configured to push data onto the stack, generate a stack-fault interrupt whenever data is pushed onto the stack, and invoke execution of a stack-fault handler in response to the stack-fault interrupt.