@ A raster scan display system includes a plurality of storage maps (MAPO to MAP4). These maps are addressable in either of two modes. In the first mode each map contains bit mapped data and the maps are addressed together to provide colour signals from which colour video signals are derived. In the second mode, one map contains character representing data and a further map, character display dot patterns. In this mode the first map is addressed to provide partial addresses for the further map. These partial addresses are combined with row scan data signals to access the further map from which the character display dot data is used to generate the video signals.