An operating access method for a DRAM is provided. A first address is obtained via an address bus and a first command is obtained via a command bus from a controller. A second address is obtained via the address bus and a second command is obtained via the command bus from the controller after the first command is obtained. The first address and the second address are combined to obtain a valid address, wherein the valid address is a row address when each of the first command and the second command is an active command. In addition, the valid address is a column address when the second command is an access command.