This paper discusses architectural issues arising from the use of dynamic reconfiguration and shows a possible use of dynamic reconfiguration to extend and accelerate a computation performed in system-on-a-chip designs with microprocessors with fixed instruction sets. The implementation data for two dynamically reconfigurable platforms available on the market - the Xilinx Virtex2 family FPGAs and the Atmel FPSLIC family FPGAs - is compared in terms of resource requirements, operating frequency, and power consumption. (en)