Method of storing character data in a display device

A method of storing character data for use in the display of characters selected from a pre-defined character set in an output image of a display device, said output image comprising a regular array of discrete pixels, the display device including a background memory, a microprocessor operable to execute machine code program instructions stored in the background memory, and a display memory, the display memory storing the output image in the form of a display bit map and having a plurality of locations which correspond to and store color data for respective pixels of the image, said method comprising;

• defining a character bit map for each character of the set, said character bit map identifying a plurality of character-shape-defining foreground pixels and a plurality of other, background pixels, each pixel having a corresponding pixel location relative to a character base location;
• encoding each character bit map to generate a machine code routine which, when executed, will cause the microprocessor to write color data to all the pixel locations of the display memory which correspond to foreground locations of the character bit map;
• and
• storing said machine code routines for the character set in the background memory of the display device;
• the step of encoding the machine code subroutine corresponding to each character of the set including the steps of identifying the relative locations of the foreground pixels of the character shape and encoding said relative locations within the instructions of the machine code subroutine in such a form that when the machine code subroutine is executed the microprocessor neither tests pixel locations of the character bit map to identify the foreground pixels, nor writes color values for the entire character bit map.