In keeping with its original purpose as a graphics language, Zgrass included numerous commands for simple drawing. Zgrass's coordinate system had one point for each pixel in the high-resolution mode of Nutting's graphics chip, giving a 320×202 grid. The Astrocade, by design, could only use that chip's low-resolution mode, a 160×101 display. To avoid potential mapping problems, the coordinate space's zero point was placed in the center of the screen. −160 to 160 were valid X locations, and -101 to 101 valid Y locations. For use on the Astrocade you used the positive locations only, whereas on the UV-1 the entire space was available.