Abstract: An integrated circuit digital processor is coupled to either a main program memory or a secondary program memory, wherein the secondary program memory may be low power, high reliability, non-volatile and/or fast memory that may store a limited number of critical program instructions and data for execution by the digital processor. A program memory switch may couple the digital processor to either the main program memory or the secondary program memory. This is particularly advantageous in that the secondary program memory may have attributes not economically feasible with the main program memory. A program memory controller may handle the selection of which of these memories that the digital processor is using to obtain its program instructions, and necessary control signals for switching and operation thereof.

Abstract: An instruction set is provided that features multiple instructions and various address modes to deliver a mixture of flexible microcontroller-like instructions and specialized digital signal processing (“DSP”) execute instructions from a single instruction stream. A subset of instructions of the instruction set can be executed by a processor. Similarly, another subset of the instructions can be utilized by the digital signal processor. A software application can thus take advantage of digital signal processing capabilities in the same program, obviating the need for separate programs for separate processors.