Dram and access and operating method thereof

An access method for a DRAM is provided. A plurality of portions of a row address of a bank corresponding to a activate command is provided. A plurality of sub-commands of the activate command are provided via a command bus, and a plurality of portions of address information regarding the portions of the row address are provided via an address bus. Each portion of the address information includes an individual portion of the row address of the bank. Each first sub-command corresponds to an individual address information. A specific sub-command of the activate command is provided via the command bus, and address information regarding a specific portion of the row address is provided. An access command corresponding to the bank is provided via the command bus after the sub-commands are provided.