A video data display terminal includes a video display, eg., a CRT, and a character buffer for storing character bytes representing characters to be displayed on the screen of the video display device. The terminal further includes microprocessing means for receiving data from a keyboard device connected thereto or alternately from a host processor for entry into the character buffer. The microprocessing means are further adapted to define one or more partitions on the screen of the video display device. Data integrity within these partitions is maintained by assigning margin attribute bytes to the margin of each partition. Refresh hardware including refresh logic control means, a line buffer, a character generator and a serializer is provided to write data within the character buffer to the video display screen.