In this paper the author presents a new approach to create a multicomputer system using MCS-51's. the interconnection of the entire system depends on a simple pair of twisted wires. As MC1488 and MC1489 are added to the 8031 serial interface to create the RS- 232 - C interface between CPU's, it is convenient to implement this kind of system or to expand a control system which uses a single CPU. this paper also analyzes topology communication protocol support. Finally, a sample is given to prove the validity of the theory.