Process and device for graphically drawing point by point a closed curve of the second order

A drawing device for carrying out a process for graphically drawing point by point at least one arc of a closed curve of the second order, wherein the plane intended to contain the curve to be drawn is divided into octants, said drawing device comprising:

• screen memory means for storing data relating to the points on a display screen defining the plane on which the closed curve of the second order is to be drawn;
• point processor means operably coupled to said screen memory means for modifying the data stored in said screen memory means at locations therein corresponding to the points of the curve to be drawn on the display screen;
• address processor means operably coupled to said screen memory means and to said point processor means for controlling access to said screen memory means and processing point data in providing the calculations necessary to accomplish an iterative point by point drawing on the display screen, said address processor means controlling the operation of said point processor means and data transfer between said point processor means and said screen memory means in the modification of the data stored in said screen memory means as a function of the curve to be drawn;
• and
• memory means operably coupled to said point processor means and to said address processor means for respectively controlling the operation thereof, said CROM memory means having instructions stored therein relating to successive changes of a reference of relative coordinates provided by director and secondary axes U,V upon successive changes in octants as the arc of the curve is drawn on the display screen and instructions relating to the iterative point by point drawing of the arc of the curve as contained in each successive octant covered by the arc of the curve to be drawn.