A design method of dual-port RAM used in the interface between Digital Signal Processors (DSP) and an interferometer is presented, in order to enable the DSP to communicate with the interferometer at a high speed. The principle and operation rule of the IDT7024 are described. According to the design, the interface circuit and flow chart are also presented. Finally, three methods are proposed to prevent the conflict of two systems according to the arbitrated access to the data exchanged between both sides.