说明：  很多嵌入式系统，特别是应用于图像处理与高速数据采集等场合的嵌入式系统，都需要高速缓存大量的数据。DDR（Double Data Rate，双数据速率）SDRAM由于其速度快、容量大，而且价格便宜，因此能够很好地满足上述场合对大量数据缓存的需求。但DDR SDRAM的接口不能直接与现今的微处理器和DSP的存储器接口相连，需要在其间插入控制器实现微处理器或DSP对存储器的控制。
(many embedded systems, especially for image processing and high-speed data acquisition, and so on the embedded system, Cache require large amounts of data. DDR (Double Data Rate, double-data rate) SDRAM due to its speed, large capacity, and their prices are cheaper, it can be a very good occasion to meet these massive data cache demand. But DDR SDRAM interface directly with today's microprocessor and DSP memory interface connected, During the need to insert controller microprocessor or DSP memory of the control.)