shapes, editing text, laying out printed pages, and playing simple games. But they did not handle colors, images, filled-in areas, black-on-white screens, or WYSIWYG fidelity to the fonts of professionally printed text.

The PDS-1 screen was repeatedly refreshed or redrawn 40 times per second to avoid visible flickering. But irregular beam motion was slower than the steady motions on raster displays. The beam deflections were driven by magnetic coils, and those