Programmable Cellular Logic: Past, Present, and Future

In recent years there has been renewed interest in the use of flexible arrays of fine-grained computational elements to perform logical functions. This interest has been sparked by the technological advancement of very large-scale integrated circuits in the form of field-programmable gate arrays (FPGAs). Although logic mapping to regular arrays of gates in integrated chip form has only been practical for the past ten years or so, a number of reconfigurable architectures were designed and analyzed during the 1960’s and early 1970’s. This paper makes a historical analysis of these structures and discusses changes in technology and architectural trends as they pertain to cellular arrays since the 1960’s. Direct comparisons of various cellular array architectural features with contemporary programmable logic features are made as well as an analysis of potential future directions for FPGA development based in part on knowledge gained from the study of cellular arrays.