A method of printing two-dimensional code symbols representing display data in encoded form, the method being performed by a host device and a printer communicating with each other, and comprising the steps of: on the side of the host device: (a) transmitting to the printer display data to be printed as a code symbol; on the side of the printer: (b) receiving the display data from the host device and storing the received display data; (c) encoding the stored display data and formatting the encoded data in accordance with a predetermined code protocol; (d) generating bitmap image data representing the code symbol from the formatted data; on the side of the host device: (e) transmitting to the printer a symbol size report request instructing the printer to transmit the symbol size to the host device; on the side of the printer: (f) calculating in response to a symbol size report request from the host device the size of the code symbol in each of its two dimensions from the bitmap image data generated in step (d); (g) transmitting to the host device as symbol size report response information corresponding to the symbol size; and (h) subject to confirmation by the host device of the symbol size, printing the code symbol based on said bitmap image data, wherein step (c) includes processes for data compression and generation of an error correction code. on the side of the host device: (a) transmitting to the printer display data to be printed as a code symbol; (a) transmitting to the printer display data to be printed as a code symbol; on the side of the printer: (b) receiving the display data from the host device and storing the received display data; (c) encoding the stored display data and formatting the encoded data in accordance with a predetermined code protocol; (d) generating bitmap image data representing the code symbol from the formatted data; (b) receiving the display data from the host device and storing the received display data; (c) encoding the stored display data and formatting the encoded data in accordance with a predetermined code protocol; (d) generating bitmap image data representing the code symbol from the formatted data; on the side of the host device: (e) transmitting to the printer a symbol size report request instructing the printer to transmit the symbol size to the host device; (e) transmitting to the printer a symbol size report request instructing the printer to transmit the symbol size to the host device; on the side of the printer: (f) calculating in response to a symbol size report request from the host device the size of the code symbol in each of its two dimensions from the bitmap image data generated in step (d); (g) transmitting to the host device as symbol size report response information corresponding to the symbol size; and (h) subject to confirmation by the host device of the symbol size, printing the code symbol based on said bitmap image data, (f) calculating in response to a symbol size report request from the host device the size of the code symbol in each of its two dimensions from the bitmap image data generated in step (d); (g) transmitting to the host device as symbol size report response information corresponding to the symbol size; and (h) subject to confirmation by the host device of the symbol size, printing the code symbol based on said bitmap image data,