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.
The simplest way to design a clocked electronic circuit is to make it perform one transfer per full cycle (rise and fall) of a clock signal. This, however, …
Double data rate - Wikipedia, the free encyclopedia