Speed of data movement measured.

Memory that transfers data faster.

Memory that processes data once.

In computing, double data rate describes a computer bus that transfers data on both the rising and falling edges of the clock signal and hence doubles the memory bandwidth by transferring data twice per clock cycle.

(QDR, or quad pumping) a communication signaling technique wherein data are transmitted at four points in the clock cycle: on the rising and falling edges, and at two intermediate points between them.

a type of static RAM computer memory that can transfer up to four words of data in each clock cycle.