What is the difference between synchronous and asynchronous interface timing?
A. The short answer is that there is absolutely no difference in the actual timing of the device. The DD-42900 Users Manual provides two sets of timing information, synchronous and asynchronous. These two sets of timing information describe the timing of the DD-42900 in two different ways. The synchronous timing information describes the read and write cycles relative to the DD-42900 clock. If the processor is running from the same clock as the DD-42900, or a derivative of this clock, then these timing diagrams and tables will provide the system designer with the shortest read and write cycle possibilities. The asynchronous timing information describes the read and write cycles of the DD-42900 without any reference to the DD-42900 clock. If your processor is using a different clock than the DD-42900 the asynchronous timing diagrams and tables provide the timing information needed to guarantee proper operation. Because the DD-42900 is a synchronous device, the read and write cycle times
