Abstract: In a system including a central processor, central memory, and local video controller communicating with a video terminal, the video terminal including a terminal processor and a video memory for storing video information for displaying on the terminal screen, a change detect circuit is provided in the local video controller for detecting whenever a change has occurred in that portion of the central memory containing video information to be displayed on the terminal's video screen. Responsive to the change detect circuit, the local video controller sends updated video information to the video memory at the terminal.The change detect circuit reduces the workload on the system by sending only the updated video information to the terminal.The change detect circuit is capable of operation with a system employing multiple terminals each having multiple independent screen display areas.