Aspects of the disclosure provide an integrated circuit (IC) chip that includes interface circuits and a control circuit. The interface circuits is configured to interface the IC chip to buses that couple the IC chip with a memory chip, to drive signals onto the buses for transmission to the memory chip and to receive signals that are transmitted on the buses from the memory chip. The control circuit is configured to receive a ratio change of transmission rates for command signals and data signals, control the interface circuits to transmit information signals to the memory chip to inform the ratio change, configure the interface circuits according to the ratio change, and allow the interface circuits to start transmit/receive signals according to the ratio change at a time.