Abstract: A communications network includes a system multiplexer (10) for effecting communication channels between a plurality of peripheral units. The peripheral units include master computers (12), (14) and (16) and various slave devices such as printers (28) and display terminals (26). The multiplexer (10) includes a receive multiplexer (30) and a transmit multiplexer (32) connected together through a communications link (34). The multiplexers are controlled through control logic circuitry (36) which receives signals from a CPU (42). The CPU (42) stores a connection pattern in the control logic circuitry (36) and alters this connection pattern to change the communications link between various peripheral devices. By multiplexing the channels, real time communication is achieved.