Adaptive Tile Refresh is a computer graphics technique for sidescrolling games, invented by id Software's John Carmack to compensate for the poor graphics performance of PCs in the early 1990s. Its principal innovation was a novel use of several EGA hardware features to perform the scrolling in hardware. The technique is named for its other aspect, the tracking of moved graphical elements in order to minimize the amount of redrawing required in every frame. Together, the combination saves the processing time that would have been required for redrawing the entire screen.