【应用笔记】Cyclone II器件和DDR及DDR2 SDRAM的接口(Interfacing DDR & DDR2 SDRAM with Cyclone II Devices)
许多年来，正如应用所不断需要的，系统越来越多地采取外部存储器作为提升性能降、低成本的一种方式。
Over the years, as applications have become more demanding, systems
have increasingly resorted to external memory as a way to boost
performance while reducing cost. Single data rate (SDR) memories gave
way to double data rate (DDR) memories as system designers continually
sought solutions to boost system performance without increasing system
complexity and cost.an361.pdf