Different levels of memory hierarchy. 

Context in source publication

Context 1

... 2-D matrices are formed by the intersection of rows (word lines) and columns (bit lines). These grid matrix like structure is called a bank and when these banks are associated in the group of two, four and eight, these banks form DDR, DDR2 and DDR3 and they form the next higher logical unit in DRAM hierarchy ( Fig.1) known as rank. ...