Spartan-3A DSP 用の BSB (Base System Builder) デザインを作成すると、次のようなエラー メッセージが表示されます。
"ERROR:Place:848 - Automatic clock placement failed. Please attempt to analyze the global clocking required for this design and either lock the clock placement or area locate the logic driven by the clocks so that the clocks may be placed in such a way that all logic driven by them may be routed. The main restriction on clock placement is that only one clock output signal for any competing Global / Side pair of clocks may enter any region. For further information see the "Quadrant Clock Routing" section in the Spartan-3 E Family Data Sheet."