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Implementation of Computation Group

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The Implementation of Computation group, under the direction of Prof. André DeHon studies how we physically implement computations. Our efforts span from algorithms and problem descriptions, through compute models, architectures, and runtime systems, and down to physical substrates, including work on design mapping between these levels. We attempt to systematically understand the design space for programmable computing devices and the impact which both substrate costs and mapping technology have on that design space. Currently, we are focusing on Programmable System-on-a-Chip designs, (what is the organization and architectural model for the integrated, heterogeneous, large capacity ICs we will soon be able to build?), interconnect (what are the fundamental interconnect requirements of a design? and how do we systematically design interconnect? how do we map onto interconnect substrates?), and ``messy'' computing (how do we guarantee correct or adequate behavior when fabrication is stochastic, devices fail both transiently and permanently during operation, and programs contain bugs?).

Research Vectors

Our goal is to understand how we physically implement computations: Given a computation to perform (domain of computations), how do we design and build an efficient device (minimum resources, maximum performance, minimum energy) out of our physical building blocks ( e.g. contemporary CMOS VLSI, molecular substrates)? How do relative costs of the physical substrate effect which solutions are most efficient (e.g. relative costs of switches versus wires)? How do we describe computations? How do we characterize the requirements of a computation? How do we algorithmically map from a high-level specification to a substrate, automatically filling in necessary implementation details? What tradeoffs do we have between algorithmic complexity and optimality guarantees when performing such mappings? What abstractions do we use to manage the complexity of these designs so that we can fully exploit the computational capabilities provided by modern and future substrates while minimizing the human effort required to exploit these substrates?

After 60 years of building computing machines, we have a large body of knowledge that addresses many pieces of these questions. However, we do not have a systematic understanding of these issues, nor do we organize and teach this material to students in a systematic way. Too much of what we know is anecdotal, historical, and relies on substrate cost assumptions which have or will change dramatically. Further, after 40 years of Moore's law, the size of systems we can physically build today is enormous. As a result, human conceptual complexity is the key limiter to the systems we can build, as well as the efficiency of the systems we build. Today's design task is simply too large and too important to tackle in an ad hoc manner.

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Room# 315, 200 South 33rd Street, Electrical and Systems Engineering Department, Philadelphia, University of Pennsylvania, PA 19104.