Updated version of an article originally published in Personal Engineering and Instrumentation News , November 1997, pages 53-55. Because these devices all use programmable interconnect, different signal arrival times coupled with asynchronous logic invite a digital disaster.
Synchronous designs are inherently safer and easier to debug than asynchronous designs.
Engineers can simply predict the behavior of synchronous systems and model them in simulation. Consequently, synchronous designs work with a much wider variation in device timing parameters and over a broader temperature range than do most asynchronous designs. As process technology improves, circuit delays decrease. A vendor might ship faster devices that meet all datasheet specifications but behave differently than the old part. Problems with asynchronous logic usually don't appear until you've built a board.