This paper discusses a novel transformation based design methodology and its use in the design of complex programmable VLSI systems. During the life cycl'e of a complex system the optimal trade-off between, partially, implementing in hardware or sofnvare is changing. This is due to varying system requirements (short time-tomarket, low-cost, low-power etc.) and improving device technology. The proposed methodology allows such redesigns to be made, using different hardware-software trade-offs, in a guaranteed correct way.