FOLDED HIERARCHICAL CROSSPOINT ARRAY

A hierarchical crosspoint array is formed by switch cells occupying separate rectangles in a common plane of an integrated circuit. The switch cells are arranged to form square subarrays which, along with a corresponding set of control cells form a compact square shaped crosspoint array. Each switch cell includes three I/O lines crossing in two orthogonal directions and mating with I/O lines of adjacent switch cells to form two orthogonal arrays of I/O lines. Pairs of orthogonal I/O lines are permanently interconnected where they intersect in switch cells along a main diagonal of the array to provide signal paths leading from separate ports along the edges of the array each extending the length and width of the crosspoint array. Each switch cell of a subarray selectively interconnects two such signal paths to provide a signal path between two ports in response to a combination of states of a bit stored in the switch cell and a bit stored in a control cell corresponding to the subarray. The control signal supplied to each subarray concurrently inhibits switch operation of all cells in the subarray. The crosspoint array can be made to quickly switch buses connected to its ports by changing only the relatively small amount of data stored in the control cells without having to change the relatively large amount of data stored in each switch cell.