An entertainment system comprised of plural game playing machines interconnected over a communication channel in which the pictures generated and displayed in the game playing machines are synchronized with external synchronization signals. In performing real-time information processing, such as a combat game, as the status change information is exchanged over a communication cable 82, game playing machines A and B enter synchronization signals transmitted from the game playing machine B via communication cable 92 to an external synchronization information input terminal 50a of a CRTC 34a of the game playing machine A. Picture signals are generated in the game playing machines A and B and pictures synchronized between the game playing machines A and B are displayed in the game playing machines 10a, 10b.