A method of managing display data involves maintaining caches (25, 29) of most recently used tiles of display data at a host (21) and at a display control device (22). The caches (25, 29) are synchronised so that they contain the same data in the same locations. When the host (21) generates a tile that needs encoding and transmitting, it checks to see if that tile is already stored in the host cache (25). If so, it sends a cache ID to the display control device (22); otherwise, it encodes and sends the tile. When the display control device (22) receives data, it identifies it either as a cache ID or as an encoded tile. If it is a cache ID, the data is retrieved from the display control device cache (29) and sent for display (23); otherwise, it decodes the tile and sends it for display (23). Both caches (25, 29) are updated so that the tile is indicated as the most recently accessed item in each cache (25, 29).