An improved architecture for a program code conversion apparatus and method for generating intermediate representations for program code conversion. The program code conversion apparatus determines which types of IR nodes to generate in an intermediate representation (IR) of subject code (10) to be translated. Depending upon the particular subject and target computing environments involved in the conversion, the program code conversion apparatus utilizes either base nodes, complex nodes, polymorphic nodes, and architecture specific nodes, or some combination thereof, in generating the intermediate representation.