Complex sentence: It is unknown quite why this version based on the old PCI design was released rather than the second generation model shown in 2006; design changes would have been minimal due to the programmable Xilinx Spartan chipset.
Split into simpler sentences: It is unknown why this version based on the old PCI design was released rather than the second generation model shown in 2006. Design changes would have been minimal due to the programmable Xilinx Spartan chipset.