Provides methods, systems and apparatus for coupling a general purpose processor (GPP) to an application specific instruction set processor (ASIP) in such a manner that the GPP can include execute instructions that do not normally comprise part of its instruction set architecture (ISA). The GPP is coupled to the ASIP via a coprocessor port such that instructions issued by the GPP to the port are conveyed to a novel pre-decoder module of the ASIP. The pre-decoder module translates the GPP instruction into operation codes for ASIP instructions to be executed in the ASIP or to an address in the ASIP instruction memory that identifies a start address for a plurality of ASIP instructions defining a complex application specific function. Once the ASIP has executed the instructions it shares the result of the execution with the GPP. In this way, the GPP takes advantage of the ASIP in its ability to more quickly execute an application specific program/procedure.