To backtrack through the prompts (or interrupt a running routine) press the ``q'' key (or right mouse button). When a routine is running, such as space-time patterns or attractor basins, the mouse disappears, To interrupt the running routine enter ``q'' (mouse presses only work when the green flashing cursor is visible, not during the running of a routine). Then backtrack to any stage in the prompt sequence with ``q`` (or right mouse button), eventually to exit the program and return to DOS.