Systems and methods for controlling memory devices are disclosed. In one embodiment, a memory system comprises a memory controller for forwarding a command signal and an address signal and for receiving and forwarding a data signal, and a first memory device for receiving the command signal and the address signal from the memory controller, where the first memory device comprises a first command judging circuit for receiving and forwarding the data signal and for decoding the command signal. The memory system further comprises a second memory device for receiving the command signal and the address signal from the memory controller, where the second memory device comprises a second command judging circuit for receiving and generating the data signal and for decoding the command signal. The command signal, the address signal and the data signal are commonly connected to the first memory device and the second memory device.