An account is given of the features and theory of operation of the file traversal display. This substantially differs from earlier equipments, in being able to pan and scroll over a large coordinate system, e.g. 32k × 32k, able to hold an extensive dynamically updated diagram as a single segment. The entire diagram may be viewed at once at reduced resolution with the possibility of smooth fractional zoom, maintaining constant line width, with automatic detail addition as magnification increases. This results from the display's ability to traverse quickly a large host-loaded display file, applying 2D transformations, clipping to a viewport, and drawing into double-buffered pixel memory at rates that allow new picture generation at up to frame rate.