Used by the routines at ROOMST and DRAW_STILL_THINGS.

The author's RESTOR. The 6144 bytes of the screen's bitmap go to LOADING_TUNE, where the loading tune was. Entering a room (ROOMST) does it twice: once when the room is drawn, as the background the scenery is drawn over, and once when the scenery is done. The compositor (COMPOSITE_TO_SCREEN) takes the background from this copy wherever it rebuilds the screen round a moving object, which is what the name is about: it is what restores the picture an object uncovers.