Configuring a wafer-scale two-dimensional array of single-bit processors

An overview of the ELSA (European large SIMD array) project, which uses a two-level strategy to achieve defect tolerance for wafer-scale architectures implemented in silicon, is presented. The target architecture is a 2-D array of processing elements for low-level image processing. An array is divided into subarrays called chips. At the chip level, defect tolerance is proved by an extra column of PEs (processing element) and bypassing techniques. At the wafer level, a double-rail connection network is used to construct a target array of defect-free chips that is as large and as fast as possible. Its main advantage is being independent of chip defects, as it is controlled from the I/O pads. An algorithm for constructing an optimized two-dimensional array on a wafer containing a given number of defect-free PEs and connections, a method to program the switches for the target architecture found by the algorithm, and software for programming the switches using laser cuts are discussed.<>