Vlsi Systems And Computations

VLSI Systems and Computations

The papers in this book were presented at the CMU Conference on VLSI Systems and Computations, held October 19-21, 1981 in Pittsburgh, Pennsylvania. The conference was organized by the Computer Science Department, Carnegie-Mellon University and was partially supported by the National Science Foundation and the Office of Naval Research. These proceedings focus on the theory and design of computational systems using VLSI. Until very recently, integrated-circuit research and development were concentrated in the device physics and fabrication design disciplines and in the integrated-circuit industry itself. Within the last few years, a community of researchers is growing to address issues closer to computer science: the relationship between computing structures and the physical structures that implement them; the specification and verification of computational procosses implemented in VLSI; the use of massively parallel computing made possible by VLSI; the design of special purpose computing architectures; and the changes in general-purpose computer architecture that VLSI makes possible. It is likely that the future exploitation of VLSI technology depends as much on structural and design innovations as on advances in fabrication technology. The book is divided into nine sections: - Invited Papers. Six distinguished researchers from industry and academia presented invited papers. - Models of Computation. The papers in this section deal with abstracting the properties of VLSI circuits into models that can be used to analyze the chip area, time or energy required for a particular computation.

VLSI Systems and Computations

An Analog VLSI System for Stereoscopic Vision

An Analog VLSI System for Stereoscopic Vision investigates the interaction of the physical medium and the computation in both biological and analog VLSI systems by synthesizing a functional neuromorphic system in silicon. In both the synthesis and analysis of the system, a point of view from within the system is adopted rather than that of an omniscient designer drawing a blueprint. This perspective projects the design and the designer into a living landscape. The motivation for a machine-centered perspective is explained in the first chapter. The second chapter describes the evolution of the silicon retina. The retina accurately encodes visual information over orders of magnitude of ambient illumination, using mismatched components that are calibrated as part of the encoding process. The visual abstraction created by the retina is suitable for transmission through a limited bandwidth channel. The third chapter introduces a general method for interchip communication, the address-event representation, which is used for transmission of retinal data. The address-event representation takes advantage of the speed of CMOS relative to biological neurons to preserve the information of biological action potentials using digital circuitry in place of axons. The fourth chapter describes a collective circuit that computes stereodisparity. In this circuit, the processing that corrects for imperfections in the hardware compensates for inherent ambiguity in the environment. The fifth chapter demonstrates a primitive working stereovision system. An Analog VLSI System for Stereoscopic Vision contributes to both computer engineering and neuroscience at a concrete level. Through the construction of a working analog of biological vision subsystems, new circuits for building brain-style analog computers have been developed. Specific neuropysiological and psychophysical results in terms of underlying electronic mechanisms are explained. These examples demonstrate the utility of using biological principles for building brain-style computers and the significance of building brain-style computers for understanding the nervous system.