Wikipedia
Double Data Rate 2 Synchronous Dynamic Random-Access Memory, officially abbreviated as DDR2 SDRAM, is a double data rate synchronous dynamic random-access memory interface. It superseded the original DDR SDRAM specification, and is superseded by DDR3 SDRAM (launched in 2007). DDR2 DIMMs are neither forward compatible with DDR3 nor backward compatible with DDR.
In addition to double pumping the data bus as in DDR SDRAM (transferring data on the rising and falling edges of the bus clock …
DDR2 SDRAM - Wikipedia, the free encyclopedia