The development of application specific instruction set processors (ASIP) is currently the exclusive domain of the semiconductor houses and core vendors. This is due to the fact that building such an architecture is a difficult task that requires expert knowledge in different domains: application software development tools, processor hardware implementation, and system integration and verification. This paper presents a retargetable framework for ASIP design which is based on machine descriptions in the LISA language. From that, software development tools can be automatically generated including HLL C-compiler, assembler, linker, simulator and debugger frontend. Moreover, synthesizable HDL code can be derived which can then be processed by standard synthesis tools. Implementation results for a low-power ASIP for DVB-T acquisition and tracking algorithms designed with the presented methodology are given.