A raster type display apparatus includes interlaced even-and-odd frames. A digital memory of a computer stores line segment data in locations which are sequentially read out to form a line segment display with overlapping line segments. The first line of one field is defined by a "O" start location and a third removed location for the end. The second line is defined by the fourth and seventh locations, and so forth. The first line of the second field starts with the last data taken plus two to access and define the line by the second and fifth locations, and so forth. The first field again reads the start to third locations, fourth to seventh, etc. Data points equal to twice the scan lines are displayed with each scan line spread over four data points. An off-scale detector prevents a line segment directly between the data points and creates a pair of line segments at the top and bottom of the display screen. An extended line from a break point in a curve to screen bottom is also prevented. Resettable registers monitor the carrier bits of digital multiplier and adder and are connected by an even-odd detector to actuate an exclusive "OR" gate to complement the output and generate the appropriate split display. A display control assigns a data words as a control which are loaded in memory by the computer. A detection network controls an "ANDED" routing network for coded control of the line segment definition, such as blanking and channel changes.
This application is a continuation of application Ser. No. 21,098, filed Mar. 16, 1979 which has been abandoned as of Mar. 12, 1981, which is a divisional application of application Ser. No. 695,100, filed June 11, 1976 now U.S. Pat. No. 4,145,754.
