Graphics computer system, a graphics system arrangement, a display

Abstract

The graphics data processor of the present invention offers as a single instruction in its instruction set a draw and advance operation. A first data register stores a set of X and Y coordinates. In a first embodiment, a predetermined color code is stored at the pixel address of a bit mapped display memory indicated by the X and Y coordinates the first data register upon execution of the draw and advance instruction. The X and Y coordinates stored in the first data register are then advanced by addition of X and Y coordinates stored In a second data register. A second embodiment is similar except that the color code stored at the X and Y coordinates of the first data register is recalled for combining with the predetermined color code and the combined result stored at that pixel location. The predetermined color code is preferably stored in another data register. By proper selection of the X and Y coordinate data stored in the second data register either the X or the Y coordinate may be altered alone or both may be simultaneously changed. Provision of signed X and Y coordinate values in the second register enables either the X or Y coordinate to be incremented or decremented. This instruction serves to enhance the speed at which a line or computed curve may be drawn in the bit mapped display.