A central processor-coprocessor assembly comprising an assembler software tool for extending the base central processor tasks into at least one coprocessor. What is important is that the assembler software tool does not need to be rebuilt when changes are made to the coprocessor elements. The invention allows assembly time extension of a base core language processing (CLP) programming model, without the need to rebuild the assembler tool itself. The assembler tool comprises a set of commands which enable the central processor to manipulate the coprocessor registers, and a coprocessor execute instruction, which initiates command processing on the coprocessor. The present invention simplifies the maintenance of the assembler tool through multiple hardware revisions by enabling hardware designers to update their coprocessor definition files to reflect new or modified coprocessors.