Automatic Layout for Gate Arrays with One Layer of Metal

Gate arrays with only one layer of metal have some advantages - notably that they are easier to make than arrays with two or three layers of metal and are correspondingly cheaper. These are countered by the increased difficulty of layout, particularly if this is to be achieved automatically by a design automation system. This paper presents an automatic layout system providing placement and routing for the C-series of uncommitted logic arrays from Ferranti; although the techniques and programs are applicable generally to gate arrays with one layer of metal.