Abstract: A display system is used for controlling an on-screen display within a display device. The on-screen display is a text information including a literal string formed by combining several numbers of letters. The display system includes a memory device for storing pieces of letter information, a controller to download a coding chart upon initialization of the display device. The coding chart includes string-forming codes and letter-forming codes. The coding chart further includes groups of string-forming codes for encoding different literal strings. The string-forming codes and the letter-forming codes correspond to the letter information in the memory. Upon receipt of an external command corresponding to a specific string-forming code, the controller fetches a letter-forming code from the coding chart based on the specific string-forming code and letter information from the memory device based on the respective letter-forming code, thereby encoding and displaying the literal string over the display screen.