sentences:  The most significant change, and the primary reason that SDRAM has supplanted asynchronous RAM, is the support for multiple internal banks inside the DRAM chip.Using a few bits of "bank address" which accompany each command, a second bank can be activated and begin reading data "while a read from the first bank is in progress".By alternating banks, an SDRAM device can keep the data bus continuously busy, in a way that asynchronous DRAM cannot.