Answer Description
DDR RAM (Double Data Rate - Random Access Memory) was designed to use two parallel channels to communicate with a motherboard's memory controller. DRAM and SDRAM use a single channel to communicate with the memory controller. While Flash Memory is capable of using multiple channels, it is non-volatile as it retains data without constant power.
Wikipedia
In computing, a computer bus operating with double data rate (DDR) transfers data on both the rising and falling edges of the clock signal This is also known as double pumped, dual-pumped, and double transition The term toggle mode is used in the context of NAND flash memory
Double_data_rate - Wikipedia, the free encyclopedia